<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2025 Workiva-->
<!--r:072bfa9f-3641-47fa-a403-6d64740721cd,g:aceadd1e-223e-4b15-af60-db1e5754d648-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/ConsolidatedStatementofStockholdersEquity" xlink:type="simple" xlink:href="anab-20250331.xsd#ConsolidatedStatementofStockholdersEquity"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/ConsolidatedStatementofStockholdersEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_88eae5b6-e8a3-4b86-8a1b-ba36118aa33e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_230314c0-4848-4ef3-8be9-dfd71c7d4e01" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_88eae5b6-e8a3-4b86-8a1b-ba36118aa33e" xlink:to="loc_us-gaap_StatementTable_230314c0-4848-4ef3-8be9-dfd71c7d4e01" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_55061470-cf0c-4b50-b733-d8e06b7e22f0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_230314c0-4848-4ef3-8be9-dfd71c7d4e01" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_55061470-cf0c-4b50-b733-d8e06b7e22f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_55061470-cf0c-4b50-b733-d8e06b7e22f0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_55061470-cf0c-4b50-b733-d8e06b7e22f0" xlink:to="loc_us-gaap_EquityComponentDomain_55061470-cf0c-4b50-b733-d8e06b7e22f0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_241ef3bb-12f1-41ba-a957-951303e55c5f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_55061470-cf0c-4b50-b733-d8e06b7e22f0" xlink:to="loc_us-gaap_EquityComponentDomain_241ef3bb-12f1-41ba-a957-951303e55c5f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_fb5034df-4ed9-4233-bade-97aacdbe8b69" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_241ef3bb-12f1-41ba-a957-951303e55c5f" xlink:to="loc_us-gaap_CommonStockMember_fb5034df-4ed9-4233-bade-97aacdbe8b69" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_f193c859-6422-48ea-8596-32e43b3559a4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_241ef3bb-12f1-41ba-a957-951303e55c5f" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_f193c859-6422-48ea-8596-32e43b3559a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_b7853bb1-27d8-44d9-9df1-ab22037eb6e9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_241ef3bb-12f1-41ba-a957-951303e55c5f" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_b7853bb1-27d8-44d9-9df1-ab22037eb6e9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_7de50c45-43a0-4985-99c4-7ed548699e46" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_241ef3bb-12f1-41ba-a957-951303e55c5f" xlink:to="loc_us-gaap_RetainedEarningsMember_7de50c45-43a0-4985-99c4-7ed548699e46" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2c3eab59-1c04-49a9-a957-6c9eb3082ce8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_88eae5b6-e8a3-4b86-8a1b-ba36118aa33e" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2c3eab59-1c04-49a9-a957-6c9eb3082ce8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_01b78f2b-1b81-48a7-a40d-3c3e8509f0bd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2c3eab59-1c04-49a9-a957-6c9eb3082ce8" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_01b78f2b-1b81-48a7-a40d-3c3e8509f0bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_28dbe89a-90c3-4cd4-8abc-ab5761088f41" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2c3eab59-1c04-49a9-a957-6c9eb3082ce8" xlink:to="loc_us-gaap_StockholdersEquity_28dbe89a-90c3-4cd4-8abc-ab5761088f41" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAndEmployeeStockPurchasePlan_93aa7886-1c12-4baf-9794-f179a0af9969" xlink:href="anab-20250331.xsd#anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAndEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2c3eab59-1c04-49a9-a957-6c9eb3082ce8" xlink:to="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAndEmployeeStockPurchasePlan_93aa7886-1c12-4baf-9794-f179a0af9969" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_StockIssuedDuringPeriodValueOptionsAndEmployeeStockPurchasePlan_46a74bfc-fb5a-41c2-bf4c-06faee73b741" xlink:href="anab-20250331.xsd#anab_StockIssuedDuringPeriodValueOptionsAndEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2c3eab59-1c04-49a9-a957-6c9eb3082ce8" xlink:to="loc_anab_StockIssuedDuringPeriodValueOptionsAndEmployeeStockPurchasePlan_46a74bfc-fb5a-41c2-bf4c-06faee73b741" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_516caf8d-7253-4785-bedd-8b971fc2103a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2c3eab59-1c04-49a9-a957-6c9eb3082ce8" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_516caf8d-7253-4785-bedd-8b971fc2103a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_52d21d59-5a56-437e-9478-074f145caa51" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2c3eab59-1c04-49a9-a957-6c9eb3082ce8" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_52d21d59-5a56-437e-9478-074f145caa51" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_57275dd7-1cff-42f2-a7e6-6e9b80d5833f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2c3eab59-1c04-49a9-a957-6c9eb3082ce8" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_57275dd7-1cff-42f2-a7e6-6e9b80d5833f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_b49774ed-214f-41b0-b6f3-eeee3879cd8c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2c3eab59-1c04-49a9-a957-6c9eb3082ce8" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_b49774ed-214f-41b0-b6f3-eeee3879cd8c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_3d8a113f-084b-4dbd-91a4-8b28de5ff07b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2c3eab59-1c04-49a9-a957-6c9eb3082ce8" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_3d8a113f-084b-4dbd-91a4-8b28de5ff07b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition_89d40af5-0654-4441-992e-ebf97dda511b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2c3eab59-1c04-49a9-a957-6c9eb3082ce8" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition_89d40af5-0654-4441-992e-ebf97dda511b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_f774d999-f4cd-4b33-99e2-abaeb2c4db03" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2c3eab59-1c04-49a9-a957-6c9eb3082ce8" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_f774d999-f4cd-4b33-99e2-abaeb2c4db03" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_08f61aff-089e-4712-a309-f22a3938e1bb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2c3eab59-1c04-49a9-a957-6c9eb3082ce8" xlink:to="loc_us-gaap_NetIncomeLoss_08f61aff-089e-4712-a309-f22a3938e1bb" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_59e6c957-ff5e-4e81-9c3a-b20ba9f67674" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_fa5565a0-421b-41b5-b5b3-1286b4d132bc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/SummaryofSignificantAccountingPoliciesSummaryofPotentiallyDilutiveSecuritiesDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#SummaryofSignificantAccountingPoliciesSummaryofPotentiallyDilutiveSecuritiesDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/SummaryofSignificantAccountingPoliciesSummaryofPotentiallyDilutiveSecuritiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_497a4b43-e010-4dc3-b679-ac6a99145838" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_4acbcd3b-3113-4386-a205-bc917a5bc70c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_497a4b43-e010-4dc3-b679-ac6a99145838" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_4acbcd3b-3113-4386-a205-bc917a5bc70c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_229f0514-9468-4e5b-812e-cc586b8a2827" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_4acbcd3b-3113-4386-a205-bc917a5bc70c" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_229f0514-9468-4e5b-812e-cc586b8a2827" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_229f0514-9468-4e5b-812e-cc586b8a2827_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_229f0514-9468-4e5b-812e-cc586b8a2827" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_229f0514-9468-4e5b-812e-cc586b8a2827_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_608ba04e-6576-43c1-814d-17b7e81b03e0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_229f0514-9468-4e5b-812e-cc586b8a2827" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_608ba04e-6576-43c1-814d-17b7e81b03e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_d72c7d07-4627-4d82-a956-db9a14e9da52" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_608ba04e-6576-43c1-814d-17b7e81b03e0" xlink:to="loc_us-gaap_EmployeeStockOptionMember_d72c7d07-4627-4d82-a956-db9a14e9da52" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockCompensationPlanMember_0e28cebf-206d-488a-8786-a5aafa166975" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockCompensationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_608ba04e-6576-43c1-814d-17b7e81b03e0" xlink:to="loc_us-gaap_StockCompensationPlanMember_0e28cebf-206d-488a-8786-a5aafa166975" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_af02d745-4fec-40bd-a888-0bc4fc984a33" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_497a4b43-e010-4dc3-b679-ac6a99145838" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_af02d745-4fec-40bd-a888-0bc4fc984a33" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/BalanceSheetAccountsandSupplementalDisclosuresScheduleofPropertyandEquipmentnetDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#BalanceSheetAccountsandSupplementalDisclosuresScheduleofPropertyandEquipmentnetDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/BalanceSheetAccountsandSupplementalDisclosuresScheduleofPropertyandEquipmentnetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_20162ab8-2652-4420-ac0a-5cb7a100a9f9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_743f3c43-ce84-45df-80c3-807516671a3e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_20162ab8-2652-4420-ac0a-5cb7a100a9f9" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_743f3c43-ce84-45df-80c3-807516671a3e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3a1f71a0-c824-4d0b-a2c6-54a9faa07e4f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_743f3c43-ce84-45df-80c3-807516671a3e" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3a1f71a0-c824-4d0b-a2c6-54a9faa07e4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3a1f71a0-c824-4d0b-a2c6-54a9faa07e4f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3a1f71a0-c824-4d0b-a2c6-54a9faa07e4f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3a1f71a0-c824-4d0b-a2c6-54a9faa07e4f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5bc298ee-3eb5-4cf4-947c-2cf2f3a0336d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3a1f71a0-c824-4d0b-a2c6-54a9faa07e4f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5bc298ee-3eb5-4cf4-947c-2cf2f3a0336d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_LaboratoryEquipmentMember_99418138-7185-4064-adc5-be40207cef3e" xlink:href="anab-20250331.xsd#anab_LaboratoryEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5bc298ee-3eb5-4cf4-947c-2cf2f3a0336d" xlink:to="loc_anab_LaboratoryEquipmentMember_99418138-7185-4064-adc5-be40207cef3e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OfficeEquipmentMember_85212403-91e8-4e3a-b4da-73f11e8241aa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OfficeEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5bc298ee-3eb5-4cf4-947c-2cf2f3a0336d" xlink:to="loc_us-gaap_OfficeEquipmentMember_85212403-91e8-4e3a-b4da-73f11e8241aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_48c81d5b-6add-4407-a045-0aa183d1d9c3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5bc298ee-3eb5-4cf4-947c-2cf2f3a0336d" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_48c81d5b-6add-4407-a045-0aa183d1d9c3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_8a5e9d2b-7008-40c2-83f3-fe144ca85b0b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_20162ab8-2652-4420-ac0a-5cb7a100a9f9" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_8a5e9d2b-7008-40c2-83f3-fe144ca85b0b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_b4f08acf-9430-4b87-9b3b-4a7bc4f23154" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_20162ab8-2652-4420-ac0a-5cb7a100a9f9" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_b4f08acf-9430-4b87-9b3b-4a7bc4f23154" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_d11f92b1-44e5-4d32-8b36-ac8536fa3030" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_20162ab8-2652-4420-ac0a-5cb7a100a9f9" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_d11f92b1-44e5-4d32-8b36-ac8536fa3030" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/CollaborativeResearchandDevelopmentAgreementsNarrativeDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#CollaborativeResearchandDevelopmentAgreementsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/CollaborativeResearchandDevelopmentAgreementsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_82de9ca7-7e81-471c-836d-a70b176ca1ee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_6c284939-86d2-433a-8959-71c970597e0e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_82de9ca7-7e81-471c-836d-a70b176ca1ee" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_6c284939-86d2-433a-8959-71c970597e0e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_ecc996f2-fbf9-4a3c-93fa-173d280f803a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_6c284939-86d2-433a-8959-71c970597e0e" xlink:to="loc_srt_CounterpartyNameAxis_ecc996f2-fbf9-4a3c-93fa-173d280f803a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_ecc996f2-fbf9-4a3c-93fa-173d280f803a_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_ecc996f2-fbf9-4a3c-93fa-173d280f803a" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_ecc996f2-fbf9-4a3c-93fa-173d280f803a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3c501a94-31d6-4280-be27-0403402f65d4" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_ecc996f2-fbf9-4a3c-93fa-173d280f803a" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3c501a94-31d6-4280-be27-0403402f65d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_GlaxoSmithKlineMember_eca652ac-68d3-4f6d-9a3f-b156d32212cb" xlink:href="anab-20250331.xsd#anab_GlaxoSmithKlineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3c501a94-31d6-4280-be27-0403402f65d4" xlink:to="loc_anab_GlaxoSmithKlineMember_eca652ac-68d3-4f6d-9a3f-b156d32212cb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_VandaPharmaceuticalsInc.Member_48ea4ece-bff1-4b9f-a083-16027999bca2" xlink:href="anab-20250331.xsd#anab_VandaPharmaceuticalsInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3c501a94-31d6-4280-be27-0403402f65d4" xlink:to="loc_anab_VandaPharmaceuticalsInc.Member_48ea4ece-bff1-4b9f-a083-16027999bca2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_CentessaPharmaceuticalsUKLimitedCentessaMember_5f9720cd-1555-447d-80c9-869c7250ff81" xlink:href="anab-20250331.xsd#anab_CentessaPharmaceuticalsUKLimitedCentessaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3c501a94-31d6-4280-be27-0403402f65d4" xlink:to="loc_anab_CentessaPharmaceuticalsUKLimitedCentessaMember_5f9720cd-1555-447d-80c9-869c7250ff81" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_c0a7cc2d-5f02-4d0e-9ceb-942989262ac5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_6c284939-86d2-433a-8959-71c970597e0e" xlink:to="loc_us-gaap_TypeOfArrangementAxis_c0a7cc2d-5f02-4d0e-9ceb-942989262ac5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_c0a7cc2d-5f02-4d0e-9ceb-942989262ac5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_c0a7cc2d-5f02-4d0e-9ceb-942989262ac5" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_c0a7cc2d-5f02-4d0e-9ceb-942989262ac5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_1fdd936c-c49f-455f-9aa9-fb2a9b4143d7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_c0a7cc2d-5f02-4d0e-9ceb-942989262ac5" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_1fdd936c-c49f-455f-9aa9-fb2a9b4143d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollaborativeArrangementMember_ecbd03cd-6826-4204-8fd8-0fb0da38e511" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CollaborativeArrangementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_1fdd936c-c49f-455f-9aa9-fb2a9b4143d7" xlink:to="loc_us-gaap_CollaborativeArrangementMember_ecbd03cd-6826-4204-8fd8-0fb0da38e511" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_RoyaltyAgreementMember_ee17a880-8c5c-46c7-9a64-a7b5d95b87fc" xlink:href="anab-20250331.xsd#anab_RoyaltyAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementMember_ecbd03cd-6826-4204-8fd8-0fb0da38e511" xlink:to="loc_anab_RoyaltyAgreementMember_ee17a880-8c5c-46c7-9a64-a7b5d95b87fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_RoyaltyAgreementUpTo10BillionMember_83246299-98ec-4c54-8820-97945f9d6af4" xlink:href="anab-20250331.xsd#anab_RoyaltyAgreementUpTo10BillionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_RoyaltyAgreementMember_ee17a880-8c5c-46c7-9a64-a7b5d95b87fc" xlink:to="loc_anab_RoyaltyAgreementUpTo10BillionMember_83246299-98ec-4c54-8820-97945f9d6af4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_RoyaltyAgreementAbove1.0BillionBelow1.5BillionMember_85b1e50a-bdd9-4649-8cd6-7127f0998338" xlink:href="anab-20250331.xsd#anab_RoyaltyAgreementAbove1.0BillionBelow1.5BillionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_RoyaltyAgreementMember_ee17a880-8c5c-46c7-9a64-a7b5d95b87fc" xlink:to="loc_anab_RoyaltyAgreementAbove1.0BillionBelow1.5BillionMember_85b1e50a-bdd9-4649-8cd6-7127f0998338" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_RoyaltyAgreementAbove1.5BillionBelow2.5BillionMember_03d66259-5da6-4435-adb3-c08891041408" xlink:href="anab-20250331.xsd#anab_RoyaltyAgreementAbove1.5BillionBelow2.5BillionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_RoyaltyAgreementMember_ee17a880-8c5c-46c7-9a64-a7b5d95b87fc" xlink:to="loc_anab_RoyaltyAgreementAbove1.5BillionBelow2.5BillionMember_03d66259-5da6-4435-adb3-c08891041408" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_RoyaltyAgreementAbove2.5BillionMember_f4c87865-6c63-4874-a002-79922102615b" xlink:href="anab-20250331.xsd#anab_RoyaltyAgreementAbove2.5BillionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_RoyaltyAgreementMember_ee17a880-8c5c-46c7-9a64-a7b5d95b87fc" xlink:to="loc_anab_RoyaltyAgreementAbove2.5BillionMember_f4c87865-6c63-4874-a002-79922102615b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_JemperliRoyaltyMonetizationAgreementMember_1e71f9a0-ad25-4dc1-943c-5020be073772" xlink:href="anab-20250331.xsd#anab_JemperliRoyaltyMonetizationAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_RoyaltyAgreementMember_ee17a880-8c5c-46c7-9a64-a7b5d95b87fc" xlink:to="loc_anab_JemperliRoyaltyMonetizationAgreementMember_1e71f9a0-ad25-4dc1-943c-5020be073772" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ZejulaRoyaltyMonetizationAgreementMember_8cd607a5-63f6-4642-9d1f-b66bdfebcf42" xlink:href="anab-20250331.xsd#anab_ZejulaRoyaltyMonetizationAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_1fdd936c-c49f-455f-9aa9-fb2a9b4143d7" xlink:to="loc_anab_ZejulaRoyaltyMonetizationAgreementMember_8cd607a5-63f6-4642-9d1f-b66bdfebcf42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ZejulaRevenueMember_7eb84472-87a3-4541-8784-a9ce02a0188b" xlink:href="anab-20250331.xsd#anab_ZejulaRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_1fdd936c-c49f-455f-9aa9-fb2a9b4143d7" xlink:to="loc_anab_ZejulaRevenueMember_7eb84472-87a3-4541-8784-a9ce02a0188b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ExclusiveLicenseAgreementMember_599c75ad-e87e-48c5-8f30-4539de55aa63" xlink:href="anab-20250331.xsd#anab_ExclusiveLicenseAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_1fdd936c-c49f-455f-9aa9-fb2a9b4143d7" xlink:to="loc_anab_ExclusiveLicenseAgreementMember_599c75ad-e87e-48c5-8f30-4539de55aa63" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_5b411ff5-2f37-4c73-98a2-95f488e99355" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_6c284939-86d2-433a-8959-71c970597e0e" xlink:to="loc_srt_RangeAxis_5b411ff5-2f37-4c73-98a2-95f488e99355" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_5b411ff5-2f37-4c73-98a2-95f488e99355_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_5b411ff5-2f37-4c73-98a2-95f488e99355" xlink:to="loc_srt_RangeMember_5b411ff5-2f37-4c73-98a2-95f488e99355_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_61f6ada6-2f25-415a-8f14-64d64e3034d0" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_5b411ff5-2f37-4c73-98a2-95f488e99355" xlink:to="loc_srt_RangeMember_61f6ada6-2f25-415a-8f14-64d64e3034d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_42eebcf3-8c61-46b0-bc8a-0453fb54014d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_61f6ada6-2f25-415a-8f14-64d64e3034d0" xlink:to="loc_srt_MinimumMember_42eebcf3-8c61-46b0-bc8a-0453fb54014d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_6b84fe2a-08b9-4739-9aa3-6bd1dfbdc36f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_61f6ada6-2f25-415a-8f14-64d64e3034d0" xlink:to="loc_srt_MaximumMember_6b84fe2a-08b9-4739-9aa3-6bd1dfbdc36f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_54cce32b-1054-4049-8cef-fe3595704b0c" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_6c284939-86d2-433a-8959-71c970597e0e" xlink:to="loc_srt_ProductOrServiceAxis_54cce32b-1054-4049-8cef-fe3595704b0c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_54cce32b-1054-4049-8cef-fe3595704b0c_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_54cce32b-1054-4049-8cef-fe3595704b0c" xlink:to="loc_srt_ProductsAndServicesDomain_54cce32b-1054-4049-8cef-fe3595704b0c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_9b42d665-205b-4174-9273-08a6dcb1c65a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_54cce32b-1054-4049-8cef-fe3595704b0c" xlink:to="loc_srt_ProductsAndServicesDomain_9b42d665-205b-4174-9273-08a6dcb1c65a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AnaptysBioGeneratedAntiPD1JemperliDostarlimabMember_52d01c8b-4fd5-47c1-af55-0537015177f4" xlink:href="anab-20250331.xsd#anab_AnaptysBioGeneratedAntiPD1JemperliDostarlimabMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_9b42d665-205b-4174-9273-08a6dcb1c65a" xlink:to="loc_anab_AnaptysBioGeneratedAntiPD1JemperliDostarlimabMember_52d01c8b-4fd5-47c1-af55-0537015177f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicenseMember_a72fa2c0-f637-4dee-9cca-832171acc308" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LicenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_9b42d665-205b-4174-9273-08a6dcb1c65a" xlink:to="loc_us-gaap_LicenseMember_a72fa2c0-f637-4dee-9cca-832171acc308" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_TransactionServiceMember_dbdeb030-0c51-43fc-9ebb-3d98cfaaf0aa" xlink:href="anab-20250331.xsd#anab_TransactionServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_9b42d665-205b-4174-9273-08a6dcb1c65a" xlink:to="loc_anab_TransactionServiceMember_dbdeb030-0c51-43fc-9ebb-3d98cfaaf0aa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_DrugSupplyMember_544a8af9-73e4-4782-bb5d-1b799408cec0" xlink:href="anab-20250331.xsd#anab_DrugSupplyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_9b42d665-205b-4174-9273-08a6dcb1c65a" xlink:to="loc_anab_DrugSupplyMember_544a8af9-73e4-4782-bb5d-1b799408cec0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionAxis_d2e422dd-20a2-4033-9248-7e864a7e5fe2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_6c284939-86d2-433a-8959-71c970597e0e" xlink:to="loc_us-gaap_AssetAcquisitionAxis_d2e422dd-20a2-4033-9248-7e864a7e5fe2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_d2e422dd-20a2-4033-9248-7e864a7e5fe2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetAcquisitionAxis_d2e422dd-20a2-4033-9248-7e864a7e5fe2" xlink:to="loc_us-gaap_AssetAcquisitionDomain_d2e422dd-20a2-4033-9248-7e864a7e5fe2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_4464c5d7-1865-4d97-93ec-76f14b7d423c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetAcquisitionAxis_d2e422dd-20a2-4033-9248-7e864a7e5fe2" xlink:to="loc_us-gaap_AssetAcquisitionDomain_4464c5d7-1865-4d97-93ec-76f14b7d423c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_LicenseAgreementCentessaPharmaceuticalsUKLimitedMember_ac7a0765-664b-4a09-aacc-5bdab71990bc" xlink:href="anab-20250331.xsd#anab_LicenseAgreementCentessaPharmaceuticalsUKLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionDomain_4464c5d7-1865-4d97-93ec-76f14b7d423c" xlink:to="loc_anab_LicenseAgreementCentessaPharmaceuticalsUKLimitedMember_ac7a0765-664b-4a09-aacc-5bdab71990bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_NetSalesRoyaltyPercent_93446b39-f1b5-40bc-b220-b7b08c991102" xlink:href="anab-20250331.xsd#anab_NetSalesRoyaltyPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_82de9ca7-7e81-471c-836d-a70b176ca1ee" xlink:to="loc_anab_NetSalesRoyaltyPercent_93446b39-f1b5-40bc-b220-b7b08c991102" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_NetSalesRoyaltyThreshold_bcca03cd-8236-4997-8fea-003d29c2db10" xlink:href="anab-20250331.xsd#anab_NetSalesRoyaltyThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_82de9ca7-7e81-471c-836d-a70b176ca1ee" xlink:to="loc_anab_NetSalesRoyaltyThreshold_bcca03cd-8236-4997-8fea-003d29c2db10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_RevenueRecognitionMilestoneMethodCommercialSaleOrExpirationOfPatentsAgreementTerm_7dcb2dcc-016a-4265-a678-7c67969efae7" xlink:href="anab-20250331.xsd#anab_RevenueRecognitionMilestoneMethodCommercialSaleOrExpirationOfPatentsAgreementTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_82de9ca7-7e81-471c-836d-a70b176ca1ee" xlink:to="loc_anab_RevenueRecognitionMilestoneMethodCommercialSaleOrExpirationOfPatentsAgreementTerm_7dcb2dcc-016a-4265-a678-7c67969efae7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_f296b0c9-9f99-49ce-ba4b-7a0203b6a232" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_82de9ca7-7e81-471c-836d-a70b176ca1ee" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_f296b0c9-9f99-49ce-ba4b-7a0203b6a232" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_CollaborativeArrangementPayment_437cccb4-6da8-4a48-bdab-218f197180cf" xlink:href="anab-20250331.xsd#anab_CollaborativeArrangementPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_82de9ca7-7e81-471c-836d-a70b176ca1ee" xlink:to="loc_anab_CollaborativeArrangementPayment_437cccb4-6da8-4a48-bdab-218f197180cf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_2fb5dd56-2026-4910-907c-31917e9b851c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_82de9ca7-7e81-471c-836d-a70b176ca1ee" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_2fb5dd56-2026-4910-907c-31917e9b851c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_CollaborativeArrangementCosts_8a5824de-72e2-4812-96ec-cd4929bd5be9" xlink:href="anab-20250331.xsd#anab_CollaborativeArrangementCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_82de9ca7-7e81-471c-836d-a70b176ca1ee" xlink:to="loc_anab_CollaborativeArrangementCosts_8a5824de-72e2-4812-96ec-cd4929bd5be9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncome_a0427105-3d1d-433f-a3c0-2a80e25bff47" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_82de9ca7-7e81-471c-836d-a70b176ca1ee" xlink:to="loc_us-gaap_DeferredIncome_a0427105-3d1d-433f-a3c0-2a80e25bff47" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_34ffdf1f-e139-4a4c-8114-3590a08f960e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsToAcquireProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_82de9ca7-7e81-471c-836d-a70b176ca1ee" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_34ffdf1f-e139-4a4c-8114-3590a08f960e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionConsiderationTransferredTransactionCost_e7c4be8d-2bc6-4d12-a862-7b475edf16d9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetAcquisitionConsiderationTransferredTransactionCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_82de9ca7-7e81-471c-836d-a70b176ca1ee" xlink:to="loc_us-gaap_AssetAcquisitionConsiderationTransferredTransactionCost_e7c4be8d-2bc6-4d12-a862-7b475edf16d9" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ReimbursementPaymentsToAcquireProductiveAssets_c50a911f-f084-4e34-a35c-3812cb37cca4" xlink:href="anab-20250331.xsd#anab_ReimbursementPaymentsToAcquireProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_82de9ca7-7e81-471c-836d-a70b176ca1ee" xlink:to="loc_anab_ReimbursementPaymentsToAcquireProductiveAssets_c50a911f-f084-4e34-a35c-3812cb37cca4" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionConsiderationTransferred_a1d6a0aa-51ea-4325-9758-69e18707c64f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetAcquisitionConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_82de9ca7-7e81-471c-836d-a70b176ca1ee" xlink:to="loc_us-gaap_AssetAcquisitionConsiderationTransferred_a1d6a0aa-51ea-4325-9758-69e18707c64f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AssetAcquisitionContingentConsiderationArrangementsRangeOfOutcomesValueHigh_9fb6e53a-cdfd-42d2-8072-f47c1d2dcbf3" xlink:href="anab-20250331.xsd#anab_AssetAcquisitionContingentConsiderationArrangementsRangeOfOutcomesValueHigh"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_82de9ca7-7e81-471c-836d-a70b176ca1ee" xlink:to="loc_anab_AssetAcquisitionContingentConsiderationArrangementsRangeOfOutcomesValueHigh_9fb6e53a-cdfd-42d2-8072-f47c1d2dcbf3" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/CollaborativeResearchandDevelopmentAgreementsScheduleofMilestoneAchievedDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#CollaborativeResearchandDevelopmentAgreementsScheduleofMilestoneAchievedDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/CollaborativeResearchandDevelopmentAgreementsScheduleofMilestoneAchievedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_3041ca97-5d2c-422f-8c0b-a5cd15957c69" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_c52571b7-b214-40f1-94fb-475be4c91eaa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3041ca97-5d2c-422f-8c0b-a5cd15957c69" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_c52571b7-b214-40f1-94fb-475be4c91eaa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_c3fd48c5-d15a-41b3-bbd6-a84d517fa540" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_c52571b7-b214-40f1-94fb-475be4c91eaa" xlink:to="loc_srt_CounterpartyNameAxis_c3fd48c5-d15a-41b3-bbd6-a84d517fa540" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_c3fd48c5-d15a-41b3-bbd6-a84d517fa540_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_c3fd48c5-d15a-41b3-bbd6-a84d517fa540" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_c3fd48c5-d15a-41b3-bbd6-a84d517fa540_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3bbfaf05-6f65-41d6-87eb-cf7f66c16067" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_c3fd48c5-d15a-41b3-bbd6-a84d517fa540" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3bbfaf05-6f65-41d6-87eb-cf7f66c16067" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_GlaxoSmithKlineMember_40a83e6d-f8fe-467d-882d-295e5e602437" xlink:href="anab-20250331.xsd#anab_GlaxoSmithKlineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3bbfaf05-6f65-41d6-87eb-cf7f66c16067" xlink:to="loc_anab_GlaxoSmithKlineMember_40a83e6d-f8fe-467d-882d-295e5e602437" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_SagardHealthcareRoyaltyPartnersLPMember_a4926db9-bf42-47bd-a32b-4f1026a160af" xlink:href="anab-20250331.xsd#anab_SagardHealthcareRoyaltyPartnersLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3bbfaf05-6f65-41d6-87eb-cf7f66c16067" xlink:to="loc_anab_SagardHealthcareRoyaltyPartnersLPMember_a4926db9-bf42-47bd-a32b-4f1026a160af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_VandaPharmaceuticalsInc.Member_4b2a57a1-dd8e-473d-8a18-24348c32490a" xlink:href="anab-20250331.xsd#anab_VandaPharmaceuticalsInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3bbfaf05-6f65-41d6-87eb-cf7f66c16067" xlink:to="loc_anab_VandaPharmaceuticalsInc.Member_4b2a57a1-dd8e-473d-8a18-24348c32490a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_b5aae154-7f58-4088-af2d-34196769146d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_c52571b7-b214-40f1-94fb-475be4c91eaa" xlink:to="loc_srt_ProductOrServiceAxis_b5aae154-7f58-4088-af2d-34196769146d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_b5aae154-7f58-4088-af2d-34196769146d_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_b5aae154-7f58-4088-af2d-34196769146d" xlink:to="loc_srt_ProductsAndServicesDomain_b5aae154-7f58-4088-af2d-34196769146d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_6cf4df70-821b-4a05-bc3c-3d23f09c0e64" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_b5aae154-7f58-4088-af2d-34196769146d" xlink:to="loc_srt_ProductsAndServicesDomain_6cf4df70-821b-4a05-bc3c-3d23f09c0e64" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AnaptysBioGeneratedAntiPD1JemperliDostarlimabMember_ddeff89e-f446-4cd0-9f0a-98cbc3eb0952" xlink:href="anab-20250331.xsd#anab_AnaptysBioGeneratedAntiPD1JemperliDostarlimabMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_6cf4df70-821b-4a05-bc3c-3d23f09c0e64" xlink:to="loc_anab_AnaptysBioGeneratedAntiPD1JemperliDostarlimabMember_ddeff89e-f446-4cd0-9f0a-98cbc3eb0952" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AnaptysBioGeneratedAntiTIM3GSK4069889ACobolimabMember_d05baef9-9e9c-4fec-859f-4760db2186f9" xlink:href="anab-20250331.xsd#anab_AnaptysBioGeneratedAntiTIM3GSK4069889ACobolimabMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_6cf4df70-821b-4a05-bc3c-3d23f09c0e64" xlink:to="loc_anab_AnaptysBioGeneratedAntiTIM3GSK4069889ACobolimabMember_d05baef9-9e9c-4fec-859f-4760db2186f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_3a14b4c5-8b4e-44df-bf7a-70a8e1a56744" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_c52571b7-b214-40f1-94fb-475be4c91eaa" xlink:to="loc_us-gaap_TypeOfArrangementAxis_3a14b4c5-8b4e-44df-bf7a-70a8e1a56744" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3a14b4c5-8b4e-44df-bf7a-70a8e1a56744_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_3a14b4c5-8b4e-44df-bf7a-70a8e1a56744" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3a14b4c5-8b4e-44df-bf7a-70a8e1a56744_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_3a14b4c5-8b4e-44df-bf7a-70a8e1a56744" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_InVivoToxicologyStudiesMember_4b6b0cd9-f179-4af8-8719-210a6800275f" xlink:href="anab-20250331.xsd#anab_InVivoToxicologyStudiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_InVivoToxicologyStudiesMember_4b6b0cd9-f179-4af8-8719-210a6800275f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ClearanceOfInvestigationalNewDrugFromFDAMember_b9e7eec1-6614-46f2-a9ed-6affe08db052" xlink:href="anab-20250331.xsd#anab_ClearanceOfInvestigationalNewDrugFromFDAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_ClearanceOfInvestigationalNewDrugFromFDAMember_b9e7eec1-6614-46f2-a9ed-6affe08db052" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_Phase2ClinicalTrialInitiationMember_d1c3eae5-0234-4ff5-b88c-79bec712987f" xlink:href="anab-20250331.xsd#anab_Phase2ClinicalTrialInitiationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_Phase2ClinicalTrialInitiationMember_d1c3eae5-0234-4ff5-b88c-79bec712987f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_Phase3ClinicalTrialInitiationFirstIndicationMember_68c733cd-71df-490b-8482-893ce857826c" xlink:href="anab-20250331.xsd#anab_Phase3ClinicalTrialInitiationFirstIndicationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_Phase3ClinicalTrialInitiationFirstIndicationMember_68c733cd-71df-490b-8482-893ce857826c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_Phase3ClinicalTrialInitiationSecondIndicationMember_47553461-f1d1-4ddb-a1d4-311eba2db53e" xlink:href="anab-20250331.xsd#anab_Phase3ClinicalTrialInitiationSecondIndicationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_Phase3ClinicalTrialInitiationSecondIndicationMember_47553461-f1d1-4ddb-a1d4-311eba2db53e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_FilingOfBiologicsLicenseApplicationFirstIndicationMember_87cff9ae-85a7-460c-855c-2d01dce288ad" xlink:href="anab-20250331.xsd#anab_FilingOfBiologicsLicenseApplicationFirstIndicationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_FilingOfBiologicsLicenseApplicationFirstIndicationMember_87cff9ae-85a7-460c-855c-2d01dce288ad" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_FilingOfMMAFirstIndicationMember_262b72e3-3600-4935-a46a-8a4245d8ba91" xlink:href="anab-20250331.xsd#anab_FilingOfMMAFirstIndicationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_FilingOfMMAFirstIndicationMember_262b72e3-3600-4935-a46a-8a4245d8ba91" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_FilingOfBiologicsLicenseApplicationSecondIndicationMember_67e82574-f035-4da8-be94-0ed0a4680abf" xlink:href="anab-20250331.xsd#anab_FilingOfBiologicsLicenseApplicationSecondIndicationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_FilingOfBiologicsLicenseApplicationSecondIndicationMember_67e82574-f035-4da8-be94-0ed0a4680abf" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_FirstBiologicsLicenseApplicationApprovalDMMRECMember_a0950765-0b68-416a-8c6a-ff8be80b9052" xlink:href="anab-20250331.xsd#anab_FirstBiologicsLicenseApplicationApprovalDMMRECMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_FirstBiologicsLicenseApplicationApprovalDMMRECMember_a0950765-0b68-416a-8c6a-ff8be80b9052" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_FirstMarketingAuthorizationApplicationApprovalFirstIndicationMember_53158fde-5fc4-4166-b662-fa85ce32f655" xlink:href="anab-20250331.xsd#anab_FirstMarketingAuthorizationApplicationApprovalFirstIndicationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_FirstMarketingAuthorizationApplicationApprovalFirstIndicationMember_53158fde-5fc4-4166-b662-fa85ce32f655" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_FirstBiologicsLicenseApplicationApprovalSecondIndicationMember_58730297-2af8-4ae8-8087-ded0d4fee2ef" xlink:href="anab-20250331.xsd#anab_FirstBiologicsLicenseApplicationApprovalSecondIndicationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_FirstBiologicsLicenseApplicationApprovalSecondIndicationMember_58730297-2af8-4ae8-8087-ded0d4fee2ef" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_FilingOfMMASecondIndicationMember_c2e32a61-0fed-44f9-92d7-0eb314ef60fa" xlink:href="anab-20250331.xsd#anab_FilingOfMMASecondIndicationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_FilingOfMMASecondIndicationMember_c2e32a61-0fed-44f9-92d7-0eb314ef60fa" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_FirstMarketingAuthorizationApplicationApprovalSecondIndicationMember_d57258ef-d5a4-4141-b635-004d14df5d10" xlink:href="anab-20250331.xsd#anab_FirstMarketingAuthorizationApplicationApprovalSecondIndicationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_FirstMarketingAuthorizationApplicationApprovalSecondIndicationMember_d57258ef-d5a4-4141-b635-004d14df5d10" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_FirstCommercialSalesMilestoneMember_cc095310-4415-451d-b822-81bd0c704ef3" xlink:href="anab-20250331.xsd#anab_FirstCommercialSalesMilestoneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_FirstCommercialSalesMilestoneMember_cc095310-4415-451d-b822-81bd0c704ef3" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_SecondCommercialSalesMilestoneMember_3dc99b55-a62b-4bb1-bd45-302b4f44b418" xlink:href="anab-20250331.xsd#anab_SecondCommercialSalesMilestoneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_SecondCommercialSalesMilestoneMember_3dc99b55-a62b-4bb1-bd45-302b4f44b418" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ThirdCommercialSalesMilestoneMember_9c1afa97-1020-4822-8e9a-2e2e60b76c74" xlink:href="anab-20250331.xsd#anab_ThirdCommercialSalesMilestoneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_ThirdCommercialSalesMilestoneMember_9c1afa97-1020-4822-8e9a-2e2e60b76c74" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_FourthCommercialSalesMilestoneMember_2c384721-6034-4461-a5b5-5e16dbb7fb8c" xlink:href="anab-20250331.xsd#anab_FourthCommercialSalesMilestoneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_FourthCommercialSalesMilestoneMember_2c384721-6034-4461-a5b5-5e16dbb7fb8c" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_CumulativeMilestonesRecognizedMember_3ac7dbe9-a251-4c1a-8e89-a0ddbcaeab36" xlink:href="anab-20250331.xsd#anab_CumulativeMilestonesRecognizedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_CumulativeMilestonesRecognizedMember_3ac7dbe9-a251-4c1a-8e89-a0ddbcaeab36" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_MilestonesYetToBeRecognizedMember_a6e59390-d0be-4b93-b59f-95c56d1c5092" xlink:href="anab-20250331.xsd#anab_MilestonesYetToBeRecognizedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_MilestonesYetToBeRecognizedMember_a6e59390-d0be-4b93-b59f-95c56d1c5092" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_JEMPERLIRoyaltyMonetizationAgreementMember_6eeb58b8-b3e2-4f2a-8285-c8438353606f" xlink:href="anab-20250331.xsd#anab_JEMPERLIRoyaltyMonetizationAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_JEMPERLIRoyaltyMonetizationAgreementMember_6eeb58b8-b3e2-4f2a-8285-c8438353606f" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_FDARegulatoryApprovalForMarketingOfFirstLicensedProductInTheUSAForTheTreatmentOfActiveFlaresInGPPMember_d1c08ef5-fb3d-49ef-bba0-7508721476e6" xlink:href="anab-20250331.xsd#anab_FDARegulatoryApprovalForMarketingOfFirstLicensedProductInTheUSAForTheTreatmentOfActiveFlaresInGPPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_FDARegulatoryApprovalForMarketingOfFirstLicensedProductInTheUSAForTheTreatmentOfActiveFlaresInGPPMember_d1c08ef5-fb3d-49ef-bba0-7508721476e6" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_RegulatoryApprovalForMarketingOfTheFirstLicensedProductInTheEUMember_8f23f320-7b58-49a6-ba7f-39be8f5c75e3" xlink:href="anab-20250331.xsd#anab_RegulatoryApprovalForMarketingOfTheFirstLicensedProductInTheEUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_RegulatoryApprovalForMarketingOfTheFirstLicensedProductInTheEUMember_8f23f320-7b58-49a6-ba7f-39be8f5c75e3" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_CommercialSalesMilestoneMember_0450ba75-25f6-4472-a97d-55fb91d147d1" xlink:href="anab-20250331.xsd#anab_CommercialSalesMilestoneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_3143c17e-d99e-40c4-93a4-107c03ec652c" xlink:to="loc_anab_CommercialSalesMilestoneMember_0450ba75-25f6-4472-a97d-55fb91d147d1" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_c591c33e-5f96-4d49-aac8-ed4923a2d7b9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3041ca97-5d2c-422f-8c0b-a5cd15957c69" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_c591c33e-5f96-4d49-aac8-ed4923a2d7b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_RevenueRecognitionMilestoneMethodContingent_471712b3-44ef-4003-a10a-fd9fb7680b74" xlink:href="anab-20250331.xsd#anab_RevenueRecognitionMilestoneMethodContingent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3041ca97-5d2c-422f-8c0b-a5cd15957c69" xlink:to="loc_anab_RevenueRecognitionMilestoneMethodContingent_471712b3-44ef-4003-a10a-fd9fb7680b74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerTimingOfSatisfactionOfPerformanceObligationAndPayment_91ca1e7e-8be5-477f-a19f-3d1146b3cbd8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerTimingOfSatisfactionOfPerformanceObligationAndPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3041ca97-5d2c-422f-8c0b-a5cd15957c69" xlink:to="loc_us-gaap_ContractWithCustomerTimingOfSatisfactionOfPerformanceObligationAndPayment_91ca1e7e-8be5-477f-a19f-3d1146b3cbd8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AdvanceFutureRoyaltiesRetainedRightsAfterAnnualSalesThresholdExceeded_e29cc191-1d92-418b-a5c4-1450caa5427d" xlink:href="anab-20250331.xsd#anab_AdvanceFutureRoyaltiesRetainedRightsAfterAnnualSalesThresholdExceeded"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3041ca97-5d2c-422f-8c0b-a5cd15957c69" xlink:to="loc_anab_AdvanceFutureRoyaltiesRetainedRightsAfterAnnualSalesThresholdExceeded_e29cc191-1d92-418b-a5c4-1450caa5427d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AdvanceFutureRoyaltiesAnnualSalesThreshold_424ca112-53af-498b-ad33-ba3b307d7ee2" xlink:href="anab-20250331.xsd#anab_AdvanceFutureRoyaltiesAnnualSalesThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3041ca97-5d2c-422f-8c0b-a5cd15957c69" xlink:to="loc_anab_AdvanceFutureRoyaltiesAnnualSalesThreshold_424ca112-53af-498b-ad33-ba3b307d7ee2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_NetSalesRoyaltyThreshold_65eef219-dd2b-4c3a-9526-9fa920644232" xlink:href="anab-20250331.xsd#anab_NetSalesRoyaltyThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3041ca97-5d2c-422f-8c0b-a5cd15957c69" xlink:to="loc_anab_NetSalesRoyaltyThreshold_65eef219-dd2b-4c3a-9526-9fa920644232" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/SaleofFutureRoyaltiesNarrativeDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#SaleofFutureRoyaltiesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/SaleofFutureRoyaltiesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_715864b4-360c-4139-81dc-2159c68614f7" xlink:href="anab-20250331.xsd#anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesTable_6d7f4320-e536-47e3-9de1-5bca7f01ffdf" xlink:href="anab-20250331.xsd#anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_715864b4-360c-4139-81dc-2159c68614f7" xlink:to="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesTable_6d7f4320-e536-47e3-9de1-5bca7f01ffdf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_9ccd66c3-ea26-4eae-b1b1-9f0f871a7b2a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesTable_6d7f4320-e536-47e3-9de1-5bca7f01ffdf" xlink:to="loc_us-gaap_TypeOfArrangementAxis_9ccd66c3-ea26-4eae-b1b1-9f0f871a7b2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_9ccd66c3-ea26-4eae-b1b1-9f0f871a7b2a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_9ccd66c3-ea26-4eae-b1b1-9f0f871a7b2a" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_9ccd66c3-ea26-4eae-b1b1-9f0f871a7b2a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_a8e97b9c-5926-4e8f-b3f9-6eafe46896d3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_9ccd66c3-ea26-4eae-b1b1-9f0f871a7b2a" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_a8e97b9c-5926-4e8f-b3f9-6eafe46896d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_JemperliRoyaltyMonetizationAgreementMember_c6e6b2ef-2733-4877-90c2-345f2b3e4364" xlink:href="anab-20250331.xsd#anab_JemperliRoyaltyMonetizationAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_a8e97b9c-5926-4e8f-b3f9-6eafe46896d3" xlink:to="loc_anab_JemperliRoyaltyMonetizationAgreementMember_c6e6b2ef-2733-4877-90c2-345f2b3e4364" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ZejulaRoyaltyMonetizationAgreementMember_3bb01d2e-683e-4d92-a55a-a28ceb79882e" xlink:href="anab-20250331.xsd#anab_ZejulaRoyaltyMonetizationAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_a8e97b9c-5926-4e8f-b3f9-6eafe46896d3" xlink:to="loc_anab_ZejulaRoyaltyMonetizationAgreementMember_3bb01d2e-683e-4d92-a55a-a28ceb79882e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_JemperliRoyaltyMonetizationAgreementAmendmentOneMember_ae8dc1be-df9c-487d-92bc-c391c44098e8" xlink:href="anab-20250331.xsd#anab_JemperliRoyaltyMonetizationAgreementAmendmentOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_a8e97b9c-5926-4e8f-b3f9-6eafe46896d3" xlink:to="loc_anab_JemperliRoyaltyMonetizationAgreementAmendmentOneMember_ae8dc1be-df9c-487d-92bc-c391c44098e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_JEMPERLIRoyaltyMonetizationAgreementMember_3d6f7582-7e1a-4843-a53e-d89e64dbcbe4" xlink:href="anab-20250331.xsd#anab_JEMPERLIRoyaltyMonetizationAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_a8e97b9c-5926-4e8f-b3f9-6eafe46896d3" xlink:to="loc_anab_JEMPERLIRoyaltyMonetizationAgreementMember_3d6f7582-7e1a-4843-a53e-d89e64dbcbe4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_5dd8e1de-4106-4f5e-91c7-2dd346560f10" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesTable_6d7f4320-e536-47e3-9de1-5bca7f01ffdf" xlink:to="loc_srt_CounterpartyNameAxis_5dd8e1de-4106-4f5e-91c7-2dd346560f10" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_5dd8e1de-4106-4f5e-91c7-2dd346560f10_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_5dd8e1de-4106-4f5e-91c7-2dd346560f10" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_5dd8e1de-4106-4f5e-91c7-2dd346560f10_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3d15cccc-3c6d-4f4b-875e-b1eb00d8c548" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_5dd8e1de-4106-4f5e-91c7-2dd346560f10" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3d15cccc-3c6d-4f4b-875e-b1eb00d8c548" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_SagardHealthcareRoyaltyPartnersLPMember_02f7823e-925d-4b22-bade-cfdd882a643d" xlink:href="anab-20250331.xsd#anab_SagardHealthcareRoyaltyPartnersLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3d15cccc-3c6d-4f4b-875e-b1eb00d8c548" xlink:to="loc_anab_SagardHealthcareRoyaltyPartnersLPMember_02f7823e-925d-4b22-bade-cfdd882a643d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_GlaxoSmithKlineMember_cdb649c5-8556-46ff-8c2d-c83849f4ce96" xlink:href="anab-20250331.xsd#anab_GlaxoSmithKlineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3d15cccc-3c6d-4f4b-875e-b1eb00d8c548" xlink:to="loc_anab_GlaxoSmithKlineMember_cdb649c5-8556-46ff-8c2d-c83849f4ce96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_DRIHealthcareTrustMember_71f14f25-4931-49a9-907a-1f4ad2e4fc05" xlink:href="anab-20250331.xsd#anab_DRIHealthcareTrustMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3d15cccc-3c6d-4f4b-875e-b1eb00d8c548" xlink:to="loc_anab_DRIHealthcareTrustMember_71f14f25-4931-49a9-907a-1f4ad2e4fc05" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AdvanceFutureRoyaltiesPaymentAxis_6e1e53e3-ceee-4e22-bdad-dcc02ea33076" xlink:href="anab-20250331.xsd#anab_AdvanceFutureRoyaltiesPaymentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesTable_6d7f4320-e536-47e3-9de1-5bca7f01ffdf" xlink:to="loc_anab_AdvanceFutureRoyaltiesPaymentAxis_6e1e53e3-ceee-4e22-bdad-dcc02ea33076" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AdvanceFutureRoyaltiesPaymentDomain_6e1e53e3-ceee-4e22-bdad-dcc02ea33076_default" xlink:href="anab-20250331.xsd#anab_AdvanceFutureRoyaltiesPaymentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_anab_AdvanceFutureRoyaltiesPaymentAxis_6e1e53e3-ceee-4e22-bdad-dcc02ea33076" xlink:to="loc_anab_AdvanceFutureRoyaltiesPaymentDomain_6e1e53e3-ceee-4e22-bdad-dcc02ea33076_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AdvanceFutureRoyaltiesPaymentDomain_01680769-400f-409e-b0ab-e003ec6b55e8" xlink:href="anab-20250331.xsd#anab_AdvanceFutureRoyaltiesPaymentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_anab_AdvanceFutureRoyaltiesPaymentAxis_6e1e53e3-ceee-4e22-bdad-dcc02ea33076" xlink:to="loc_anab_AdvanceFutureRoyaltiesPaymentDomain_01680769-400f-409e-b0ab-e003ec6b55e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_FirstInstallmentMember_aa672413-60b3-432d-a232-e39bb9199688" xlink:href="anab-20250331.xsd#anab_FirstInstallmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_AdvanceFutureRoyaltiesPaymentDomain_01680769-400f-409e-b0ab-e003ec6b55e8" xlink:to="loc_anab_FirstInstallmentMember_aa672413-60b3-432d-a232-e39bb9199688" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_SecondInstallmentMember_566bda7a-bac6-46e7-988e-f096650a307f" xlink:href="anab-20250331.xsd#anab_SecondInstallmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_AdvanceFutureRoyaltiesPaymentDomain_01680769-400f-409e-b0ab-e003ec6b55e8" xlink:to="loc_anab_SecondInstallmentMember_566bda7a-bac6-46e7-988e-f096650a307f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ProceedsFromAdvanceFutureRoyalties_0bd443f3-af6d-4577-b172-a98c4f65f225" xlink:href="anab-20250331.xsd#anab_ProceedsFromAdvanceFutureRoyalties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_715864b4-360c-4139-81dc-2159c68614f7" xlink:to="loc_anab_ProceedsFromAdvanceFutureRoyalties_0bd443f3-af6d-4577-b172-a98c4f65f225" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AdvanceFutureRoyaltiesAggregateAdditionalPayment_4fac769f-6c06-4781-a6b5-d6a276ccce95" xlink:href="anab-20250331.xsd#anab_AdvanceFutureRoyaltiesAggregateAdditionalPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_715864b4-360c-4139-81dc-2159c68614f7" xlink:to="loc_anab_AdvanceFutureRoyaltiesAggregateAdditionalPayment_4fac769f-6c06-4781-a6b5-d6a276ccce95" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_CumulativeRepaymentOfAdvanceFutureRoyaltyAndMilestones_fdc0b7be-1674-46ac-984b-f77722777fa7" xlink:href="anab-20250331.xsd#anab_CumulativeRepaymentOfAdvanceFutureRoyaltyAndMilestones"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_715864b4-360c-4139-81dc-2159c68614f7" xlink:to="loc_anab_CumulativeRepaymentOfAdvanceFutureRoyaltyAndMilestones_fdc0b7be-1674-46ac-984b-f77722777fa7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AdvanceFutureRoyaltiesRetainedRightsAfterAnnualSalesThresholdExceeded_e12e7ebc-fe93-4d5d-a01b-d1ded7701e42" xlink:href="anab-20250331.xsd#anab_AdvanceFutureRoyaltiesRetainedRightsAfterAnnualSalesThresholdExceeded"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_715864b4-360c-4139-81dc-2159c68614f7" xlink:to="loc_anab_AdvanceFutureRoyaltiesRetainedRightsAfterAnnualSalesThresholdExceeded_e12e7ebc-fe93-4d5d-a01b-d1ded7701e42" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AdvanceFutureRoyaltiesAnnualSalesThreshold_da23fd90-6397-4b74-b47a-f897a759d396" xlink:href="anab-20250331.xsd#anab_AdvanceFutureRoyaltiesAnnualSalesThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_715864b4-360c-4139-81dc-2159c68614f7" xlink:to="loc_anab_AdvanceFutureRoyaltiesAnnualSalesThreshold_da23fd90-6397-4b74-b47a-f897a759d396" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AdvanceFutureRoyaltiesIssuanceCosts_8afe3bdf-03f4-4514-b161-5b3219cece21" xlink:href="anab-20250331.xsd#anab_AdvanceFutureRoyaltiesIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_715864b4-360c-4139-81dc-2159c68614f7" xlink:to="loc_anab_AdvanceFutureRoyaltiesIssuanceCosts_8afe3bdf-03f4-4514-b161-5b3219cece21" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AdvanceFutureRoyaltiesLiabilityNoncurrentNet_ac3bb430-4af8-4464-adc9-a982c6ae2242" xlink:href="anab-20250331.xsd#anab_AdvanceFutureRoyaltiesLiabilityNoncurrentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_715864b4-360c-4139-81dc-2159c68614f7" xlink:to="loc_anab_AdvanceFutureRoyaltiesLiabilityNoncurrentNet_ac3bb430-4af8-4464-adc9-a982c6ae2242" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AdvanceFutureRoyaltiesInterestRateEffectivePercentage_338d75fa-2113-4d71-aa48-84a077067acd" xlink:href="anab-20250331.xsd#anab_AdvanceFutureRoyaltiesInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_715864b4-360c-4139-81dc-2159c68614f7" xlink:to="loc_anab_AdvanceFutureRoyaltiesInterestRateEffectivePercentage_338d75fa-2113-4d71-aa48-84a077067acd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_0a70aed8-ef63-4969-a0cd-6b7655f01778" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_715864b4-360c-4139-81dc-2159c68614f7" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_0a70aed8-ef63-4969-a0cd-6b7655f01778" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_NoncashAdvanceFutureRoyaltiesAndAmortizationOfAdvanceFutureRoyaltiesInterestExpense_9a589b58-f6ec-41b9-bdd5-e2dfc0c001de" xlink:href="anab-20250331.xsd#anab_NoncashAdvanceFutureRoyaltiesAndAmortizationOfAdvanceFutureRoyaltiesInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_715864b4-360c-4139-81dc-2159c68614f7" xlink:to="loc_anab_NoncashAdvanceFutureRoyaltiesAndAmortizationOfAdvanceFutureRoyaltiesInterestExpense_9a589b58-f6ec-41b9-bdd5-e2dfc0c001de" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AdvanceFutureRoyaltiesMinimumGlobalNetSalesRate_e74cb729-9e8e-4d0f-83e7-655735af9524" xlink:href="anab-20250331.xsd#anab_AdvanceFutureRoyaltiesMinimumGlobalNetSalesRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_715864b4-360c-4139-81dc-2159c68614f7" xlink:to="loc_anab_AdvanceFutureRoyaltiesMinimumGlobalNetSalesRate_e74cb729-9e8e-4d0f-83e7-655735af9524" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AdvanceFutureRoyaltiesLiabilityNoncurrent_69814582-1f95-4b1c-bb14-32427ca5db58" xlink:href="anab-20250331.xsd#anab_AdvanceFutureRoyaltiesLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_715864b4-360c-4139-81dc-2159c68614f7" xlink:to="loc_anab_AdvanceFutureRoyaltiesLiabilityNoncurrent_69814582-1f95-4b1c-bb14-32427ca5db58" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_NoncashAdvanceFutureRoyaltiesInterestExpense_720c5613-aaa1-4889-af5a-f74082ee497d" xlink:href="anab-20250331.xsd#anab_NoncashAdvanceFutureRoyaltiesInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_715864b4-360c-4139-81dc-2159c68614f7" xlink:to="loc_anab_NoncashAdvanceFutureRoyaltiesInterestExpense_720c5613-aaa1-4889-af5a-f74082ee497d" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/SaleofFutureRoyaltiesScheduleofRoyaltyTransactionActivityDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#SaleofFutureRoyaltiesScheduleofRoyaltyTransactionActivityDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/SaleofFutureRoyaltiesScheduleofRoyaltyTransactionActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_bbaa4447-7613-4017-ab55-e63e259050d4" xlink:href="anab-20250331.xsd#anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesTable_2bd213cc-38fb-496b-afd7-5040a943ee7c" xlink:href="anab-20250331.xsd#anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_bbaa4447-7613-4017-ab55-e63e259050d4" xlink:to="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesTable_2bd213cc-38fb-496b-afd7-5040a943ee7c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_d52fa991-aa25-4ee3-a495-5a5118079b86" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesTable_2bd213cc-38fb-496b-afd7-5040a943ee7c" xlink:to="loc_us-gaap_TypeOfArrangementAxis_d52fa991-aa25-4ee3-a495-5a5118079b86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_d52fa991-aa25-4ee3-a495-5a5118079b86_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_d52fa991-aa25-4ee3-a495-5a5118079b86" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_d52fa991-aa25-4ee3-a495-5a5118079b86_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_2e16938e-98b8-430b-ba3f-59c0236f3cc7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_d52fa991-aa25-4ee3-a495-5a5118079b86" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_2e16938e-98b8-430b-ba3f-59c0236f3cc7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_JemperliRoyaltyMonetizationAgreementMember_6d654f2a-c81f-4160-809a-52a6510870cf" xlink:href="anab-20250331.xsd#anab_JemperliRoyaltyMonetizationAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_2e16938e-98b8-430b-ba3f-59c0236f3cc7" xlink:to="loc_anab_JemperliRoyaltyMonetizationAgreementMember_6d654f2a-c81f-4160-809a-52a6510870cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ZejulaRoyaltyMonetizationAgreementMember_de323523-c4f2-4663-9cc0-695f3911eba6" xlink:href="anab-20250331.xsd#anab_ZejulaRoyaltyMonetizationAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_2e16938e-98b8-430b-ba3f-59c0236f3cc7" xlink:to="loc_anab_ZejulaRoyaltyMonetizationAgreementMember_de323523-c4f2-4663-9cc0-695f3911eba6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesRollForward_23068f7f-4da6-478a-8c5b-ae86df0d138d" xlink:href="anab-20250331.xsd#anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_bbaa4447-7613-4017-ab55-e63e259050d4" xlink:to="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesRollForward_23068f7f-4da6-478a-8c5b-ae86df0d138d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AdvanceFutureRoyaltiesLiabilities_8d99574b-3f80-4e49-bd7b-6ef64201c9b6" xlink:href="anab-20250331.xsd#anab_AdvanceFutureRoyaltiesLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesRollForward_23068f7f-4da6-478a-8c5b-ae86df0d138d" xlink:to="loc_anab_AdvanceFutureRoyaltiesLiabilities_8d99574b-3f80-4e49-bd7b-6ef64201c9b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AmortizationOfAdvanceFutureRoyaltiesIssuanceCosts_6365f05b-6834-4a2b-a1a4-193ccd4ab171" xlink:href="anab-20250331.xsd#anab_AmortizationOfAdvanceFutureRoyaltiesIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesRollForward_23068f7f-4da6-478a-8c5b-ae86df0d138d" xlink:to="loc_anab_AmortizationOfAdvanceFutureRoyaltiesIssuanceCosts_6365f05b-6834-4a2b-a1a4-193ccd4ab171" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_RepaymentOfAdvanceFutureRoyaltyAndMilestones_33af5ae0-ebd0-4d4f-ad08-478c4fb6d040" xlink:href="anab-20250331.xsd#anab_RepaymentOfAdvanceFutureRoyaltyAndMilestones"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesRollForward_23068f7f-4da6-478a-8c5b-ae86df0d138d" xlink:to="loc_anab_RepaymentOfAdvanceFutureRoyaltyAndMilestones_33af5ae0-ebd0-4d4f-ad08-478c4fb6d040" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_NoncashAdvanceFutureRoyaltiesInterestExpense_1dde9136-64c8-40bc-b525-296df89b0642" xlink:href="anab-20250331.xsd#anab_NoncashAdvanceFutureRoyaltiesInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesRollForward_23068f7f-4da6-478a-8c5b-ae86df0d138d" xlink:to="loc_anab_NoncashAdvanceFutureRoyaltiesInterestExpense_1dde9136-64c8-40bc-b525-296df89b0642" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AdvanceFutureRoyaltiesLiabilities_6cb93b6e-7e8f-4e33-b056-aeed231fbc85" xlink:href="anab-20250331.xsd#anab_AdvanceFutureRoyaltiesLiabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_NoncashInterestExpenseNegativeAmortization_48ed3d92-3d78-4f60-8bbe-d12514bd7575" xlink:href="anab-20250331.xsd#anab_NoncashInterestExpenseNegativeAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_LiabilitiesRelatedToSaleOfFutureRoyaltiesLineItems_bbaa4447-7613-4017-ab55-e63e259050d4" xlink:to="loc_anab_NoncashInterestExpenseNegativeAmortization_48ed3d92-3d78-4f60-8bbe-d12514bd7575" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/FairValueMeasurementsandAvailableforSaleInvestmentsScheduleofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#FairValueMeasurementsandAvailableforSaleInvestmentsScheduleofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/FairValueMeasurementsandAvailableforSaleInvestmentsScheduleofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f31c6cd9-b20f-4994-b018-313c48bca1c0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_3fcd403a-b3fd-476a-a15a-b3ef6ac07098" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f31c6cd9-b20f-4994-b018-313c48bca1c0" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_3fcd403a-b3fd-476a-a15a-b3ef6ac07098" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_117e07e0-2fc8-497f-996b-0f1fe5997906" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_3fcd403a-b3fd-476a-a15a-b3ef6ac07098" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_117e07e0-2fc8-497f-996b-0f1fe5997906" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_117e07e0-2fc8-497f-996b-0f1fe5997906_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_117e07e0-2fc8-497f-996b-0f1fe5997906" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_117e07e0-2fc8-497f-996b-0f1fe5997906_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_07c9999a-1cb6-4ca0-962f-1b49eff50018" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_117e07e0-2fc8-497f-996b-0f1fe5997906" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_07c9999a-1cb6-4ca0-962f-1b49eff50018" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_3c9b1682-c476-4183-ba76-7ac8f7c64c6e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_07c9999a-1cb6-4ca0-962f-1b49eff50018" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_3c9b1682-c476-4183-ba76-7ac8f7c64c6e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2c1918ae-f286-4ac8-8256-e7e10fb874fc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_3fcd403a-b3fd-476a-a15a-b3ef6ac07098" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2c1918ae-f286-4ac8-8256-e7e10fb874fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2c1918ae-f286-4ac8-8256-e7e10fb874fc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2c1918ae-f286-4ac8-8256-e7e10fb874fc" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2c1918ae-f286-4ac8-8256-e7e10fb874fc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_086ce4a0-aade-4742-9384-c44d07aded70" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2c1918ae-f286-4ac8-8256-e7e10fb874fc" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_086ce4a0-aade-4742-9384-c44d07aded70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_c60800e7-1cf5-43d0-952d-fe00fba7c556" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_086ce4a0-aade-4742-9384-c44d07aded70" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_c60800e7-1cf5-43d0-952d-fe00fba7c556" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_d2cbdd00-1b0a-425e-9870-cc0f68659fa6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_086ce4a0-aade-4742-9384-c44d07aded70" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_d2cbdd00-1b0a-425e-9870-cc0f68659fa6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_39345750-3d26-4fcf-b24f-62eb6ab5f8ba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_086ce4a0-aade-4742-9384-c44d07aded70" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_39345750-3d26-4fcf-b24f-62eb6ab5f8ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_12a9bb35-1ccd-4ee9-9324-f08978977b66" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_3fcd403a-b3fd-476a-a15a-b3ef6ac07098" xlink:to="loc_us-gaap_FinancialInstrumentAxis_12a9bb35-1ccd-4ee9-9324-f08978977b66" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_12a9bb35-1ccd-4ee9-9324-f08978977b66_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_12a9bb35-1ccd-4ee9-9324-f08978977b66" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_12a9bb35-1ccd-4ee9-9324-f08978977b66_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5fb46ec4-18cf-45e3-9571-ffcfae66383c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_12a9bb35-1ccd-4ee9-9324-f08978977b66" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5fb46ec4-18cf-45e3-9571-ffcfae66383c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_23a6ce45-1bf5-4770-8fb6-b1e4c7d941dc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5fb46ec4-18cf-45e3-9571-ffcfae66383c" xlink:to="loc_us-gaap_MoneyMarketFundsMember_23a6ce45-1bf5-4770-8fb6-b1e4c7d941dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MutualFundMember_e9b57c5a-5999-4393-87b6-002df074c972" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MutualFundMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5fb46ec4-18cf-45e3-9571-ffcfae66383c" xlink:to="loc_us-gaap_MutualFundMember_e9b57c5a-5999-4393-87b6-002df074c972" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_ebd9822b-599a-4a8f-9728-6f574dd820b6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5fb46ec4-18cf-45e3-9571-ffcfae66383c" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_ebd9822b-599a-4a8f-9728-6f574dd820b6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_a25e033e-24f5-4b03-b125-2cb2f82a20e3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5fb46ec4-18cf-45e3-9571-ffcfae66383c" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_a25e033e-24f5-4b03-b125-2cb2f82a20e3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_CommercialAndCorporateObligationsMember_9f708c0c-a280-4df7-af80-9b1c1dc690ee" xlink:href="anab-20250331.xsd#anab_CommercialAndCorporateObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5fb46ec4-18cf-45e3-9571-ffcfae66383c" xlink:to="loc_anab_CommercialAndCorporateObligationsMember_9f708c0c-a280-4df7-af80-9b1c1dc690ee" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_269c573e-f4ee-4ba4-a0e1-2aea52504951" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f31c6cd9-b20f-4994-b018-313c48bca1c0" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_269c573e-f4ee-4ba4-a0e1-2aea52504951" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_b094d79d-4424-411e-aa47-f78f66f6e349" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f31c6cd9-b20f-4994-b018-313c48bca1c0" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_b094d79d-4424-411e-aa47-f78f66f6e349" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/FairValueMeasurementsandAvailableforSaleInvestmentsScheduleofAvailableforsaleInvestmentsDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#FairValueMeasurementsandAvailableforSaleInvestmentsScheduleofAvailableforsaleInvestmentsDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/FairValueMeasurementsandAvailableforSaleInvestmentsScheduleofAvailableforsaleInvestmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_70b6a946-1b8d-425f-a44d-7e1003cdd9e3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_0682dc3c-6c6c-4f2c-80aa-b74ef8655dd1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_70b6a946-1b8d-425f-a44d-7e1003cdd9e3" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_0682dc3c-6c6c-4f2c-80aa-b74ef8655dd1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_3ec4f7e5-8a3d-4a34-a8cb-287b30a2136f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_0682dc3c-6c6c-4f2c-80aa-b74ef8655dd1" xlink:to="loc_us-gaap_FinancialInstrumentAxis_3ec4f7e5-8a3d-4a34-a8cb-287b30a2136f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3ec4f7e5-8a3d-4a34-a8cb-287b30a2136f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_3ec4f7e5-8a3d-4a34-a8cb-287b30a2136f" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3ec4f7e5-8a3d-4a34-a8cb-287b30a2136f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5cf8120b-c2e2-4cf2-94be-240f6fdc29d9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_3ec4f7e5-8a3d-4a34-a8cb-287b30a2136f" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5cf8120b-c2e2-4cf2-94be-240f6fdc29d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_9a9d5b8d-0526-4295-8719-6d5e87eeab18" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5cf8120b-c2e2-4cf2-94be-240f6fdc29d9" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_9a9d5b8d-0526-4295-8719-6d5e87eeab18" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_CommercialAndCorporateObligationsMember_f86f2ddd-b514-4e0d-af7a-6bb2c92031c6" xlink:href="anab-20250331.xsd#anab_CommercialAndCorporateObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5cf8120b-c2e2-4cf2-94be-240f6fdc29d9" xlink:to="loc_anab_CommercialAndCorporateObligationsMember_f86f2ddd-b514-4e0d-af7a-6bb2c92031c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_a2934810-eec3-446e-8766-1d7fce3d8b9a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5cf8120b-c2e2-4cf2-94be-240f6fdc29d9" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_a2934810-eec3-446e-8766-1d7fce3d8b9a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_d44ea7e2-6fd2-4980-bd29-c665eb700db1" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_0682dc3c-6c6c-4f2c-80aa-b74ef8655dd1" xlink:to="loc_srt_RangeAxis_d44ea7e2-6fd2-4980-bd29-c665eb700db1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_d44ea7e2-6fd2-4980-bd29-c665eb700db1_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_d44ea7e2-6fd2-4980-bd29-c665eb700db1" xlink:to="loc_srt_RangeMember_d44ea7e2-6fd2-4980-bd29-c665eb700db1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_e1120ef3-8574-4612-aaf3-f07b0773697f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_d44ea7e2-6fd2-4980-bd29-c665eb700db1" xlink:to="loc_srt_RangeMember_e1120ef3-8574-4612-aaf3-f07b0773697f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_172eb879-6da4-48bc-80e5-bffc18ac9983" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_e1120ef3-8574-4612-aaf3-f07b0773697f" xlink:to="loc_srt_MinimumMember_172eb879-6da4-48bc-80e5-bffc18ac9983" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_b6b60be5-38e6-4f3e-a49a-72663e4b6434" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_e1120ef3-8574-4612-aaf3-f07b0773697f" xlink:to="loc_srt_MaximumMember_b6b60be5-38e6-4f3e-a49a-72663e4b6434" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_97d969e5-d6ea-4402-ad5f-4b46b1e93b74" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_70b6a946-1b8d-425f-a44d-7e1003cdd9e3" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_97d969e5-d6ea-4402-ad5f-4b46b1e93b74" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_33cf6559-1729-48ae-9b44-e2d75807f6f1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_70b6a946-1b8d-425f-a44d-7e1003cdd9e3" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_33cf6559-1729-48ae-9b44-e2d75807f6f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_7b9e5280-4c15-4395-95d7-5658931a6165" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_70b6a946-1b8d-425f-a44d-7e1003cdd9e3" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_7b9e5280-4c15-4395-95d7-5658931a6165" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_7e208dd6-7f6c-4168-aea5-55a17c31489d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_70b6a946-1b8d-425f-a44d-7e1003cdd9e3" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_7e208dd6-7f6c-4168-aea5-55a17c31489d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent_84656f1d-e839-4ef3-ac29-30cacea8129c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_70b6a946-1b8d-425f-a44d-7e1003cdd9e3" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent_84656f1d-e839-4ef3-ac29-30cacea8129c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesNoncurrent_30e3c221-a4d1-40d8-8922-fb16b4c8dba5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecuritiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_70b6a946-1b8d-425f-a44d-7e1003cdd9e3" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesNoncurrent_30e3c221-a4d1-40d8-8922-fb16b4c8dba5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AvailableforsaleDebtSecuritiesRemainingMaturity_c0c398f5-dfae-4c49-afc5-00c511613964" xlink:href="anab-20250331.xsd#anab_AvailableforsaleDebtSecuritiesRemainingMaturity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_70b6a946-1b8d-425f-a44d-7e1003cdd9e3" xlink:to="loc_anab_AvailableforsaleDebtSecuritiesRemainingMaturity_c0c398f5-dfae-4c49-afc5-00c511613964" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/FairValueMeasurementsandAvailableforSaleInvestmentsScheduleofUnrealizedLossandFairValuesinaLossPositionDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#FairValueMeasurementsandAvailableforSaleInvestmentsScheduleofUnrealizedLossandFairValuesinaLossPositionDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/FairValueMeasurementsandAvailableforSaleInvestmentsScheduleofUnrealizedLossandFairValuesinaLossPositionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_ac256d82-1ade-4319-9221-7e66dc81b80b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_c8c71cbc-cca2-4ce5-a6e2-4b6a5add7e44" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_ac256d82-1ade-4319-9221-7e66dc81b80b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_c8c71cbc-cca2-4ce5-a6e2-4b6a5add7e44" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_37559379-5c12-4034-8dae-43dcbfefe8b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_c8c71cbc-cca2-4ce5-a6e2-4b6a5add7e44" xlink:to="loc_us-gaap_FinancialInstrumentAxis_37559379-5c12-4034-8dae-43dcbfefe8b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_37559379-5c12-4034-8dae-43dcbfefe8b3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_37559379-5c12-4034-8dae-43dcbfefe8b3" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_37559379-5c12-4034-8dae-43dcbfefe8b3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_eaacacba-ada2-4128-9a06-23d70d62920b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_37559379-5c12-4034-8dae-43dcbfefe8b3" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_eaacacba-ada2-4128-9a06-23d70d62920b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_9ecb9058-3c2a-4b9c-adda-2d7b6031b63a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_eaacacba-ada2-4128-9a06-23d70d62920b" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_9ecb9058-3c2a-4b9c-adda-2d7b6031b63a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_CommercialAndCorporateObligationsMember_f62b982b-33cf-4d22-a49d-ed42e2478730" xlink:href="anab-20250331.xsd#anab_CommercialAndCorporateObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_eaacacba-ada2-4128-9a06-23d70d62920b" xlink:to="loc_anab_CommercialAndCorporateObligationsMember_f62b982b-33cf-4d22-a49d-ed42e2478730" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_d1b343cd-46fd-45c9-b949-a08f6bfa07d6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_eaacacba-ada2-4128-9a06-23d70d62920b" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_d1b343cd-46fd-45c9-b949-a08f6bfa07d6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_01e268ac-8752-48d5-98c2-4f58b237eee2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_ac256d82-1ade-4319-9221-7e66dc81b80b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_01e268ac-8752-48d5-98c2-4f58b237eee2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_5769aa21-7b5d-4161-a7dd-143fc7e1a702" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_ac256d82-1ade-4319-9221-7e66dc81b80b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_5769aa21-7b5d-4161-a7dd-143fc7e1a702" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_720e3b85-b3e2-4278-9c1f-9b9abf1e6bc1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_ac256d82-1ade-4319-9221-7e66dc81b80b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_720e3b85-b3e2-4278-9c1f-9b9abf1e6bc1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_f5991b5b-c84a-4362-95de-d9402b93b0e9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_ac256d82-1ade-4319-9221-7e66dc81b80b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_f5991b5b-c84a-4362-95de-d9402b93b0e9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_b461c70c-7705-4762-8182-231a5f2f2620" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_ac256d82-1ade-4319-9221-7e66dc81b80b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_b461c70c-7705-4762-8182-231a5f2f2620" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_8ecdc086-3976-452f-b81f-296d18bd3c0e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_ac256d82-1ade-4319-9221-7e66dc81b80b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_8ecdc086-3976-452f-b81f-296d18bd3c0e" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/StockholdersEquityNarrativeDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#StockholdersEquityNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/StockholdersEquityNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_710a6436-e185-4ff5-a66f-53c0019c2636" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_e3ee8dae-e27f-439e-8da2-1397c834ddfb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_710a6436-e185-4ff5-a66f-53c0019c2636" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_e3ee8dae-e27f-439e-8da2-1397c834ddfb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_6b5bf031-1354-4144-84d5-ccad3ef62ffc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_e3ee8dae-e27f-439e-8da2-1397c834ddfb" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_6b5bf031-1354-4144-84d5-ccad3ef62ffc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_6b5bf031-1354-4144-84d5-ccad3ef62ffc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_6b5bf031-1354-4144-84d5-ccad3ef62ffc" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_6b5bf031-1354-4144-84d5-ccad3ef62ffc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_6a726cea-fea2-4d65-a7e7-f1bac1f5dc8d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_6b5bf031-1354-4144-84d5-ccad3ef62ffc" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_6a726cea-fea2-4d65-a7e7-f1bac1f5dc8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_OpenMarketSalesAgreementMember_95fc3c5d-8b37-4e25-bcf2-2f0ef60cc342" xlink:href="anab-20250331.xsd#anab_OpenMarketSalesAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_6a726cea-fea2-4d65-a7e7-f1bac1f5dc8d" xlink:to="loc_anab_OpenMarketSalesAgreementMember_95fc3c5d-8b37-4e25-bcf2-2f0ef60cc342" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_UnderwritingAgreementMember_f53fbe1e-81d8-4b83-85c2-7db36164c759" xlink:href="anab-20250331.xsd#anab_UnderwritingAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_6a726cea-fea2-4d65-a7e7-f1bac1f5dc8d" xlink:to="loc_anab_UnderwritingAgreementMember_f53fbe1e-81d8-4b83-85c2-7db36164c759" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_14f3ac91-cfb7-4918-b47e-f8907b6988f9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_710a6436-e185-4ff5-a66f-53c0019c2636" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_14f3ac91-cfb7-4918-b47e-f8907b6988f9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_b45d931e-8463-4b71-98b0-9c1232610a8f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_710a6436-e185-4ff5-a66f-53c0019c2636" xlink:to="loc_us-gaap_CommonStockSharesIssued_b45d931e-8463-4b71-98b0-9c1232610a8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_731af548-e123-4d4d-bd2b-3ca5daa824e5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_710a6436-e185-4ff5-a66f-53c0019c2636" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_731af548-e123-4d4d-bd2b-3ca5daa824e5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_40995d05-92e3-4907-817b-fc9ab92c035f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_710a6436-e185-4ff5-a66f-53c0019c2636" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_40995d05-92e3-4907-817b-fc9ab92c035f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_148f3317-1860-4c4e-9aca-5381c52f8caf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_710a6436-e185-4ff5-a66f-53c0019c2636" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_148f3317-1860-4c4e-9aca-5381c52f8caf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_SaleOfStockAuthorizedAggregateOfferingMaximum_ee66a13f-5c23-4308-9667-6c8960fa727c" xlink:href="anab-20250331.xsd#anab_SaleOfStockAuthorizedAggregateOfferingMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_710a6436-e185-4ff5-a66f-53c0019c2636" xlink:to="loc_anab_SaleOfStockAuthorizedAggregateOfferingMaximum_ee66a13f-5c23-4308-9667-6c8960fa727c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_ee5ae1f3-45a6-4095-a463-d635e5dfeedd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_710a6436-e185-4ff5-a66f-53c0019c2636" xlink:to="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_ee5ae1f3-45a6-4095-a463-d635e5dfeedd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesIssuedPricePerShare_56095411-f3dc-431f-83cf-5f7bd9c5f3a1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharesIssuedPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_710a6436-e185-4ff5-a66f-53c0019c2636" xlink:to="loc_us-gaap_SharesIssuedPricePerShare_56095411-f3dc-431f-83cf-5f7bd9c5f3a1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_2b310dce-b39b-447a-8cca-5056498cddf9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_710a6436-e185-4ff5-a66f-53c0019c2636" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_2b310dce-b39b-447a-8cca-5056498cddf9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_PaymentsOfStockIssuanceCostsAndUnderwritingDiscountsAndCommissions_29cacf79-a785-4e00-b18a-f9ee4b5266c6" xlink:href="anab-20250331.xsd#anab_PaymentsOfStockIssuanceCostsAndUnderwritingDiscountsAndCommissions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_710a6436-e185-4ff5-a66f-53c0019c2636" xlink:to="loc_anab_PaymentsOfStockIssuanceCostsAndUnderwritingDiscountsAndCommissions_29cacf79-a785-4e00-b18a-f9ee4b5266c6" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/EquityIncentivePlansNarrativeDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#EquityIncentivePlansNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/EquityIncentivePlansNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2092b3d0-cdb8-414f-a10d-711e29f3b499" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_16d91462-36d7-4172-a2e3-2cac84405c1d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2092b3d0-cdb8-414f-a10d-711e29f3b499" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_16d91462-36d7-4172-a2e3-2cac84405c1d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_1a6f5c5e-bb54-465b-a1d0-130e6415ad3d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_16d91462-36d7-4172-a2e3-2cac84405c1d" xlink:to="loc_us-gaap_PlanNameAxis_1a6f5c5e-bb54-465b-a1d0-130e6415ad3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_1a6f5c5e-bb54-465b-a1d0-130e6415ad3d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_1a6f5c5e-bb54-465b-a1d0-130e6415ad3d" xlink:to="loc_us-gaap_PlanNameDomain_1a6f5c5e-bb54-465b-a1d0-130e6415ad3d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_1f5e03da-a6d5-44f7-a642-f71e5d9872b6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_1a6f5c5e-bb54-465b-a1d0-130e6415ad3d" xlink:to="loc_us-gaap_PlanNameDomain_1f5e03da-a6d5-44f7-a642-f71e5d9872b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_EquityIncentivePlan2017Member_b3e84f95-0571-4bb9-984c-88140fbae655" xlink:href="anab-20250331.xsd#anab_EquityIncentivePlan2017Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_1f5e03da-a6d5-44f7-a642-f71e5d9872b6" xlink:to="loc_anab_EquityIncentivePlan2017Member_b3e84f95-0571-4bb9-984c-88140fbae655" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_EmployeeStockPurchasePlan2017Member_49cd8257-8504-43bf-801c-190a95eaef2d" xlink:href="anab-20250331.xsd#anab_EmployeeStockPurchasePlan2017Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_1f5e03da-a6d5-44f7-a642-f71e5d9872b6" xlink:to="loc_anab_EmployeeStockPurchasePlan2017Member_49cd8257-8504-43bf-801c-190a95eaef2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_eb519fad-9be4-4d0f-aa17-5ec75fd459d6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_16d91462-36d7-4172-a2e3-2cac84405c1d" xlink:to="loc_us-gaap_AwardTypeAxis_eb519fad-9be4-4d0f-aa17-5ec75fd459d6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eb519fad-9be4-4d0f-aa17-5ec75fd459d6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_eb519fad-9be4-4d0f-aa17-5ec75fd459d6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eb519fad-9be4-4d0f-aa17-5ec75fd459d6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10257200-709c-4324-ae75-3751461ac075" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_eb519fad-9be4-4d0f-aa17-5ec75fd459d6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10257200-709c-4324-ae75-3751461ac075" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_6a44ae32-bda1-462d-851a-2f9fd0465697" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10257200-709c-4324-ae75-3751461ac075" xlink:to="loc_us-gaap_EmployeeStockMember_6a44ae32-bda1-462d-851a-2f9fd0465697" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_b5f17433-e5f9-4104-af4c-6d53274125a2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10257200-709c-4324-ae75-3751461ac075" xlink:to="loc_us-gaap_EmployeeStockOptionMember_b5f17433-e5f9-4104-af4c-6d53274125a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_7d18471e-acce-4ea3-bc68-179d489cd070" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10257200-709c-4324-ae75-3751461ac075" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_7d18471e-acce-4ea3-bc68-179d489cd070" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_b4f825a7-9cb0-4d88-9d9e-f1bfd1b921b5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10257200-709c-4324-ae75-3751461ac075" xlink:to="loc_us-gaap_PerformanceSharesMember_b4f825a7-9cb0-4d88-9d9e-f1bfd1b921b5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_175b637a-c06b-44e1-b36e-f6a07ca915ee" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_16d91462-36d7-4172-a2e3-2cac84405c1d" xlink:to="loc_srt_TitleOfIndividualAxis_175b637a-c06b-44e1-b36e-f6a07ca915ee" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_175b637a-c06b-44e1-b36e-f6a07ca915ee_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_175b637a-c06b-44e1-b36e-f6a07ca915ee" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_175b637a-c06b-44e1-b36e-f6a07ca915ee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_85119495-28c7-4865-8dde-460387d3f07e" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_175b637a-c06b-44e1-b36e-f6a07ca915ee" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_85119495-28c7-4865-8dde-460387d3f07e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_DirectorMember_aa261ad5-276c-4644-8fbe-155b55484f66" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_DirectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_85119495-28c7-4865-8dde-460387d3f07e" xlink:to="loc_srt_DirectorMember_aa261ad5-276c-4644-8fbe-155b55484f66" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_CommonStockCapitalSharesReservedForFutureIssuanceAnnualIncreasePercentOfAggregateSharesOutstanding_9889ba86-2138-4b6b-ad7f-17e0e2806d21" xlink:href="anab-20250331.xsd#anab_CommonStockCapitalSharesReservedForFutureIssuanceAnnualIncreasePercentOfAggregateSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2092b3d0-cdb8-414f-a10d-711e29f3b499" xlink:to="loc_anab_CommonStockCapitalSharesReservedForFutureIssuanceAnnualIncreasePercentOfAggregateSharesOutstanding_9889ba86-2138-4b6b-ad7f-17e0e2806d21" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_b2468fe0-d320-42cb-b5f8-a40f3b1073fe" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2092b3d0-cdb8-414f-a10d-711e29f3b499" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_b2468fe0-d320-42cb-b5f8-a40f3b1073fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_6299f87d-e9d9-4909-8805-d3ff278bb275" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2092b3d0-cdb8-414f-a10d-711e29f3b499" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_6299f87d-e9d9-4909-8805-d3ff278bb275" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssued_b7a79f5a-81ad-4358-b409-2913ae5ae92b" xlink:href="anab-20250331.xsd#anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2092b3d0-cdb8-414f-a10d-711e29f3b499" xlink:to="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssued_b7a79f5a-81ad-4358-b409-2913ae5ae92b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_b1cbe879-7777-4d65-9db5-5b45bfa457cc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2092b3d0-cdb8-414f-a10d-711e29f3b499" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_b1cbe879-7777-4d65-9db5-5b45bfa457cc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_9c68e34d-acbc-4d83-b5c5-96415c3d5812" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2092b3d0-cdb8-414f-a10d-711e29f3b499" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_9c68e34d-acbc-4d83-b5c5-96415c3d5812" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_697aa313-c656-483d-84f1-1fe41d9172c1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2092b3d0-cdb8-414f-a10d-711e29f3b499" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_697aa313-c656-483d-84f1-1fe41d9172c1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardCommonShareEquivalent_2817ce85-0382-4d3e-862b-76ba5ea5cc0e" xlink:href="anab-20250331.xsd#anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardCommonShareEquivalent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2092b3d0-cdb8-414f-a10d-711e29f3b499" xlink:to="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardCommonShareEquivalent_2817ce85-0382-4d3e-862b-76ba5ea5cc0e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesIssuable_51310e10-7505-4ee2-96b8-766dcdad9319" xlink:href="anab-20250331.xsd#anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2092b3d0-cdb8-414f-a10d-711e29f3b499" xlink:to="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesIssuable_51310e10-7505-4ee2-96b8-766dcdad9319" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_8ff43214-e572-42cc-92cb-08639e1ac9b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2092b3d0-cdb8-414f-a10d-711e29f3b499" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_8ff43214-e572-42cc-92cb-08639e1ac9b3" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_a56a9b27-e76c-4cf1-8342-996615cbb56b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2092b3d0-cdb8-414f-a10d-711e29f3b499" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_a56a9b27-e76c-4cf1-8342-996615cbb56b" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/EquityIncentivePlansScheduleofTimebasedRestrictedStockUnitsPSUsDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#EquityIncentivePlansScheduleofTimebasedRestrictedStockUnitsPSUsDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/EquityIncentivePlansScheduleofTimebasedRestrictedStockUnitsPSUsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2a538689-06e8-474d-b829-f0b27210b543" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f788a524-a007-4cb6-adbb-e50c9dd32d64" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2a538689-06e8-474d-b829-f0b27210b543" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f788a524-a007-4cb6-adbb-e50c9dd32d64" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_3c787c9c-ced2-4fe8-9668-c781c69b1d29" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f788a524-a007-4cb6-adbb-e50c9dd32d64" xlink:to="loc_us-gaap_AwardTypeAxis_3c787c9c-ced2-4fe8-9668-c781c69b1d29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3c787c9c-ced2-4fe8-9668-c781c69b1d29_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_3c787c9c-ced2-4fe8-9668-c781c69b1d29" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3c787c9c-ced2-4fe8-9668-c781c69b1d29_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cfeb30ea-5da1-4c87-8c92-750d9f12f3fa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_3c787c9c-ced2-4fe8-9668-c781c69b1d29" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cfeb30ea-5da1-4c87-8c92-750d9f12f3fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_87bd1bf0-ff6d-4c5b-a7df-b84756ce8517" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cfeb30ea-5da1-4c87-8c92-750d9f12f3fa" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_87bd1bf0-ff6d-4c5b-a7df-b84756ce8517" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_551c3f36-da3f-4899-b619-85d33827637f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cfeb30ea-5da1-4c87-8c92-750d9f12f3fa" xlink:to="loc_us-gaap_PerformanceSharesMember_551c3f36-da3f-4899-b619-85d33827637f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_72f34075-d374-4241-93f7-2af60fa280de" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2a538689-06e8-474d-b829-f0b27210b543" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_72f34075-d374-4241-93f7-2af60fa280de" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_15e6aa08-4669-44b2-9a3f-130cb580c39d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_72f34075-d374-4241-93f7-2af60fa280de" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_15e6aa08-4669-44b2-9a3f-130cb580c39d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_5ac70836-01a2-4b4b-b2cb-0b1575fa7033" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_72f34075-d374-4241-93f7-2af60fa280de" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_5ac70836-01a2-4b4b-b2cb-0b1575fa7033" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_c07e60b8-ea02-439c-ba5e-4d6772049468" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_72f34075-d374-4241-93f7-2af60fa280de" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_c07e60b8-ea02-439c-ba5e-4d6772049468" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_749f05e6-5667-4c73-b705-80ef23f1af2b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_72f34075-d374-4241-93f7-2af60fa280de" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_749f05e6-5667-4c73-b705-80ef23f1af2b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_d43e9dfe-2f66-4052-8188-0e48e6a79ee5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestOutstandingNumber_424509a3-c377-47a6-afd4-08e06da388c9" xlink:href="anab-20250331.xsd#anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2a538689-06e8-474d-b829-f0b27210b543" xlink:to="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestOutstandingNumber_424509a3-c377-47a6-afd4-08e06da388c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_dd51408b-c523-4d32-b084-089ae8051675" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2a538689-06e8-474d-b829-f0b27210b543" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_dd51408b-c523-4d32-b084-089ae8051675" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_0626489c-e325-41d2-800f-b3c312939258" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_dd51408b-c523-4d32-b084-089ae8051675" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_0626489c-e325-41d2-800f-b3c312939258" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_4666402c-d848-48fc-b5b6-9d4033c9c10b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_dd51408b-c523-4d32-b084-089ae8051675" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_4666402c-d848-48fc-b5b6-9d4033c9c10b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_5452857d-0a9f-4b51-9d07-b8a885f5cbfa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_dd51408b-c523-4d32-b084-089ae8051675" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_5452857d-0a9f-4b51-9d07-b8a885f5cbfa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_426e1dac-965f-4a99-af57-c97d2a867279" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_dd51408b-c523-4d32-b084-089ae8051675" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_426e1dac-965f-4a99-af57-c97d2a867279" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_507aac2b-6e4d-4dd4-8f42-ef6b5811754f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestOutstandingWeightedAverageGrantDateFairValue_ad227617-f225-4e54-9d7c-e9cce89dbdb4" xlink:href="anab-20250331.xsd#anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestOutstandingWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2a538689-06e8-474d-b829-f0b27210b543" xlink:to="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestOutstandingWeightedAverageGrantDateFairValue_ad227617-f225-4e54-9d7c-e9cce89dbdb4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_b50c4633-81fd-4a15-b3e8-0b50f6543355" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2a538689-06e8-474d-b829-f0b27210b543" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_b50c4633-81fd-4a15-b3e8-0b50f6543355" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_b72aa20e-2e6d-42a8-a531-4dc5eac1ad0f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_b50c4633-81fd-4a15-b3e8-0b50f6543355" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_b72aa20e-2e6d-42a8-a531-4dc5eac1ad0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerms_8767942e-fd74-48c9-a6dd-9e5abda3d590" xlink:href="anab-20250331.xsd#anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_b50c4633-81fd-4a15-b3e8-0b50f6543355" xlink:to="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerms_8767942e-fd74-48c9-a6dd-9e5abda3d590" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueNonvested_298ce6fa-0e63-4189-ba35-13c9bbe7eeea" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueNonvested"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_b50c4633-81fd-4a15-b3e8-0b50f6543355" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueNonvested_298ce6fa-0e63-4189-ba35-13c9bbe7eeea" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_a122e6c3-c46d-4a85-a639-4861b1323428" xlink:href="anab-20250331.xsd#anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_b50c4633-81fd-4a15-b3e8-0b50f6543355" xlink:to="loc_anab_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_a122e6c3-c46d-4a85-a639-4861b1323428" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/EquityIncentivePlansScheduleofGrantDateFairValueAssumptionsDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#EquityIncentivePlansScheduleofGrantDateFairValueAssumptionsDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/EquityIncentivePlansScheduleofGrantDateFairValueAssumptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_05fffa0b-1584-4346-9cbe-44480b787220" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5328fe4e-c6a0-47c7-8686-1d6356d2816c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_05fffa0b-1584-4346-9cbe-44480b787220" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5328fe4e-c6a0-47c7-8686-1d6356d2816c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_fcf9c4fb-f7be-4d93-a7b7-c06dfc2dfce8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5328fe4e-c6a0-47c7-8686-1d6356d2816c" xlink:to="loc_us-gaap_AwardTypeAxis_fcf9c4fb-f7be-4d93-a7b7-c06dfc2dfce8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_fcf9c4fb-f7be-4d93-a7b7-c06dfc2dfce8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_fcf9c4fb-f7be-4d93-a7b7-c06dfc2dfce8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_fcf9c4fb-f7be-4d93-a7b7-c06dfc2dfce8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6a1e3429-1c55-48a3-b496-813322d5ad5a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_fcf9c4fb-f7be-4d93-a7b7-c06dfc2dfce8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6a1e3429-1c55-48a3-b496-813322d5ad5a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_3e82befd-b419-4920-801f-4980d63beb4c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6a1e3429-1c55-48a3-b496-813322d5ad5a" xlink:to="loc_us-gaap_PerformanceSharesMember_3e82befd-b419-4920-801f-4980d63beb4c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_c9a85243-fc89-4722-840e-856352618412" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_05fffa0b-1584-4346-9cbe-44480b787220" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_c9a85243-fc89-4722-840e-856352618412" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_8fe27f1f-a592-439f-89b9-7b076fe3691e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_05fffa0b-1584-4346-9cbe-44480b787220" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_8fe27f1f-a592-439f-89b9-7b076fe3691e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_1ce65a70-b59f-487d-8f25-a709ad591046" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_05fffa0b-1584-4346-9cbe-44480b787220" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_1ce65a70-b59f-487d-8f25-a709ad591046" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/EquityIncentivePlansScheduleofWeightedAverageAssumptionsusedtoEstimateFairValueDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#EquityIncentivePlansScheduleofWeightedAverageAssumptionsusedtoEstimateFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/EquityIncentivePlansScheduleofWeightedAverageAssumptionsusedtoEstimateFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_707cba5b-2120-4026-b141-6bc5554d46ba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_58f8eb06-f8ed-4d82-b35a-16cc37875558" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_707cba5b-2120-4026-b141-6bc5554d46ba" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_58f8eb06-f8ed-4d82-b35a-16cc37875558" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_702e0a2c-a029-402d-9275-f57139c9e9f7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_58f8eb06-f8ed-4d82-b35a-16cc37875558" xlink:to="loc_us-gaap_AwardTypeAxis_702e0a2c-a029-402d-9275-f57139c9e9f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_702e0a2c-a029-402d-9275-f57139c9e9f7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_702e0a2c-a029-402d-9275-f57139c9e9f7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_702e0a2c-a029-402d-9275-f57139c9e9f7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_edf2476e-81ff-41d4-9c8c-a8bd1cfa0735" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_702e0a2c-a029-402d-9275-f57139c9e9f7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_edf2476e-81ff-41d4-9c8c-a8bd1cfa0735" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_629124b7-f20f-409c-959a-cf1817328537" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_edf2476e-81ff-41d4-9c8c-a8bd1cfa0735" xlink:to="loc_us-gaap_EmployeeStockOptionMember_629124b7-f20f-409c-959a-cf1817328537" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_467db067-0d6f-4b7e-b2b6-62d1e1825de3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_707cba5b-2120-4026-b141-6bc5554d46ba" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_467db067-0d6f-4b7e-b2b6-62d1e1825de3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_4920b521-5872-4fa7-8cde-455ee26bdc70" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_707cba5b-2120-4026-b141-6bc5554d46ba" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_4920b521-5872-4fa7-8cde-455ee26bdc70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_211cb0d3-564a-41de-a8ca-54a2b6542e73" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_707cba5b-2120-4026-b141-6bc5554d46ba" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_211cb0d3-564a-41de-a8ca-54a2b6542e73" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_7d0ff480-29ff-4711-85c8-a181159bac3e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_707cba5b-2120-4026-b141-6bc5554d46ba" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_7d0ff480-29ff-4711-85c8-a181159bac3e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_ee60de6c-32af-4492-a563-5eda2215fadd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_707cba5b-2120-4026-b141-6bc5554d46ba" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_ee60de6c-32af-4492-a563-5eda2215fadd" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/EquityIncentivePlansScheduleofAllocationofSharebasedCompensationExpenseDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#EquityIncentivePlansScheduleofAllocationofSharebasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/EquityIncentivePlansScheduleofAllocationofSharebasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7853c06c-ac4f-4eb1-ab45-743bf9677c51" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b6a7f5d2-12e5-44ae-a7cc-1b99a661ae79" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7853c06c-ac4f-4eb1-ab45-743bf9677c51" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b6a7f5d2-12e5-44ae-a7cc-1b99a661ae79" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_f34f69a5-18cb-4799-a48a-527ba15b11ab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b6a7f5d2-12e5-44ae-a7cc-1b99a661ae79" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_f34f69a5-18cb-4799-a48a-527ba15b11ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_f34f69a5-18cb-4799-a48a-527ba15b11ab_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_f34f69a5-18cb-4799-a48a-527ba15b11ab" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_f34f69a5-18cb-4799-a48a-527ba15b11ab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_916b5486-6c19-4be3-8a01-ba66b8b74a7e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_f34f69a5-18cb-4799-a48a-527ba15b11ab" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_916b5486-6c19-4be3-8a01-ba66b8b74a7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_40cfa433-d2e0-45ae-b257-2f229c6313f5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_916b5486-6c19-4be3-8a01-ba66b8b74a7e" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_40cfa433-d2e0-45ae-b257-2f229c6313f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_af36527f-3054-4fcf-a60f-b27302901fd8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GeneralAndAdministrativeExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_916b5486-6c19-4be3-8a01-ba66b8b74a7e" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_af36527f-3054-4fcf-a60f-b27302901fd8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_cffefee0-2bf8-4f54-b797-1c7ea4505279" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b6a7f5d2-12e5-44ae-a7cc-1b99a661ae79" xlink:to="loc_srt_TitleOfIndividualAxis_cffefee0-2bf8-4f54-b797-1c7ea4505279" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_cffefee0-2bf8-4f54-b797-1c7ea4505279_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_cffefee0-2bf8-4f54-b797-1c7ea4505279" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_cffefee0-2bf8-4f54-b797-1c7ea4505279_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_9f24af14-c7be-4e7f-bce2-8cae6a84e315" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_cffefee0-2bf8-4f54-b797-1c7ea4505279" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_9f24af14-c7be-4e7f-bce2-8cae6a84e315" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ChiefExecutiveOfficerMember_f75a9589-aa97-412e-9095-86fbe1eb492f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ChiefExecutiveOfficerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_9f24af14-c7be-4e7f-bce2-8cae6a84e315" xlink:to="loc_srt_ChiefExecutiveOfficerMember_f75a9589-aa97-412e-9095-86fbe1eb492f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_419706d8-5fe1-4b6a-a46c-609de3105a38" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b6a7f5d2-12e5-44ae-a7cc-1b99a661ae79" xlink:to="loc_us-gaap_AwardTypeAxis_419706d8-5fe1-4b6a-a46c-609de3105a38" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_419706d8-5fe1-4b6a-a46c-609de3105a38_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_419706d8-5fe1-4b6a-a46c-609de3105a38" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_419706d8-5fe1-4b6a-a46c-609de3105a38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2134bc39-b8f3-4ad3-85de-e644f394d591" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_419706d8-5fe1-4b6a-a46c-609de3105a38" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2134bc39-b8f3-4ad3-85de-e644f394d591" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_0670a53e-ebb9-4623-ac70-0b18ee36dac6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2134bc39-b8f3-4ad3-85de-e644f394d591" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_0670a53e-ebb9-4623-ac70-0b18ee36dac6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_b81a7f16-54f3-4125-b169-be70d9c8a067" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7853c06c-ac4f-4eb1-ab45-743bf9677c51" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_b81a7f16-54f3-4125-b169-be70d9c8a067" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_8ddac7f9-4e3a-4c6c-9c45-5defac187df8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7853c06c-ac4f-4eb1-ab45-743bf9677c51" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_8ddac7f9-4e3a-4c6c-9c45-5defac187df8" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/CommitmentsandContingenciesNarrativeDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#CommitmentsandContingenciesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/CommitmentsandContingenciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_de9b7c54-e718-44e9-839d-d0475726c724" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_97e5cf58-fb53-4f34-b2f4-c700644dc377" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_de9b7c54-e718-44e9-839d-d0475726c724" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_97e5cf58-fb53-4f34-b2f4-c700644dc377" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_bedff9d2-7d76-4fbe-96b0-f6992c6cfa88" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_97e5cf58-fb53-4f34-b2f4-c700644dc377" xlink:to="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_bedff9d2-7d76-4fbe-96b0-f6992c6cfa88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_bedff9d2-7d76-4fbe-96b0-f6992c6cfa88_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_bedff9d2-7d76-4fbe-96b0-f6992c6cfa88" xlink:to="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_bedff9d2-7d76-4fbe-96b0-f6992c6cfa88_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_19544b17-5f07-4d84-8267-e60f0abf359a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_bedff9d2-7d76-4fbe-96b0-f6992c6cfa88" xlink:to="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_19544b17-5f07-4d84-8267-e60f0abf359a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_A10770WateridgeCircleSanDiegoCalifornia92121Member_88d0da25-f877-4634-8621-cc55c5757200" xlink:href="anab-20250331.xsd#anab_A10770WateridgeCircleSanDiegoCalifornia92121Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_19544b17-5f07-4d84-8267-e60f0abf359a" xlink:to="loc_anab_A10770WateridgeCircleSanDiegoCalifornia92121Member_88d0da25-f877-4634-8621-cc55c5757200" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AreaOfRealEstateProperty_49774e76-21c0-42c4-af2f-c3abc9077d67" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AreaOfRealEstateProperty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_de9b7c54-e718-44e9-839d-d0475726c724" xlink:to="loc_us-gaap_AreaOfRealEstateProperty_49774e76-21c0-42c4-af2f-c3abc9077d67" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_fcf129c2-6b40-4d5d-b867-46007075bae5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_de9b7c54-e718-44e9-839d-d0475726c724" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_fcf129c2-6b40-4d5d-b867-46007075bae5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_a68c98a1-a59e-4c57-bf6a-c65b3a768cae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_de9b7c54-e718-44e9-839d-d0475726c724" xlink:to="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_a68c98a1-a59e-4c57-bf6a-c65b3a768cae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_LesseeOperatingLeaseExpirationPeriod_5de669ff-ac3b-4cd4-ac0d-138fdff7ec23" xlink:href="anab-20250331.xsd#anab_LesseeOperatingLeaseExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_de9b7c54-e718-44e9-839d-d0475726c724" xlink:to="loc_anab_LesseeOperatingLeaseExpirationPeriod_5de669ff-ac3b-4cd4-ac0d-138fdff7ec23" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_RentPerSquareFoot_18c3ba58-f140-4eef-b0e4-ae1c49ccab6a" xlink:href="anab-20250331.xsd#anab_RentPerSquareFoot"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_de9b7c54-e718-44e9-839d-d0475726c724" xlink:to="loc_anab_RentPerSquareFoot_18c3ba58-f140-4eef-b0e4-ae1c49ccab6a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_AnnualRentIncreasePercent_bf2dbc8f-7f78-4932-bddb-0b20e27eb893" xlink:href="anab-20250331.xsd#anab_AnnualRentIncreasePercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_de9b7c54-e718-44e9-839d-d0475726c724" xlink:to="loc_anab_AnnualRentIncreasePercent_bf2dbc8f-7f78-4932-bddb-0b20e27eb893" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_68707c90-5f27-40a4-ae0b-8045858f8569" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_de9b7c54-e718-44e9-839d-d0475726c724" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_68707c90-5f27-40a4-ae0b-8045858f8569" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_1beaa744-eb5e-4839-bb23-b517d45366c2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_de9b7c54-e718-44e9-839d-d0475726c724" xlink:to="loc_us-gaap_OperatingLeaseLiability_1beaa744-eb5e-4839-bb23-b517d45366c2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecurityDeposit_178520a9-89ba-47f0-9613-f801b66c4485" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecurityDeposit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_de9b7c54-e718-44e9-839d-d0475726c724" xlink:to="loc_us-gaap_SecurityDeposit_178520a9-89ba-47f0-9613-f801b66c4485" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_2b9c6cae-218f-47b8-8702-bd217070fb30" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_de9b7c54-e718-44e9-839d-d0475726c724" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_2b9c6cae-218f-47b8-8702-bd217070fb30" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_c260eeb8-3e19-4bf2-8ba9-6c7927c456e4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_de9b7c54-e718-44e9-839d-d0475726c724" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_c260eeb8-3e19-4bf2-8ba9-6c7927c456e4" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anaptysbio.com/role/SegmentReportingScheduleofRevenuebyMajorCustomersbyReportingSegmentsDetails" xlink:type="simple" xlink:href="anab-20250331.xsd#SegmentReportingScheduleofRevenuebyMajorCustomersbyReportingSegmentsDetails"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/SegmentReportingScheduleofRevenuebyMajorCustomersbyReportingSegmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_def95231-48b2-44f0-b7b6-4fc26b922c3f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6f9464cf-b7ae-44c0-b1e6-f522e27ad9d3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_def95231-48b2-44f0-b7b6-4fc26b922c3f" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6f9464cf-b7ae-44c0-b1e6-f522e27ad9d3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_85ccb1d0-7303-4356-abb4-ba909110748c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6f9464cf-b7ae-44c0-b1e6-f522e27ad9d3" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_85ccb1d0-7303-4356-abb4-ba909110748c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_85ccb1d0-7303-4356-abb4-ba909110748c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_85ccb1d0-7303-4356-abb4-ba909110748c" xlink:to="loc_us-gaap_SegmentDomain_85ccb1d0-7303-4356-abb4-ba909110748c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_9057c59c-f30c-4f97-98fb-cf81bd0bc56c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_85ccb1d0-7303-4356-abb4-ba909110748c" xlink:to="loc_us-gaap_SegmentDomain_9057c59c-f30c-4f97-98fb-cf81bd0bc56c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ResearchAndDevelopmentSegmentMember_f1cd8294-e9a7-43b5-8776-3bff605a712d" xlink:href="anab-20250331.xsd#anab_ResearchAndDevelopmentSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_9057c59c-f30c-4f97-98fb-cf81bd0bc56c" xlink:to="loc_anab_ResearchAndDevelopmentSegmentMember_f1cd8294-e9a7-43b5-8776-3bff605a712d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_83000482-fcaa-472a-baeb-681ebe60573d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6f9464cf-b7ae-44c0-b1e6-f522e27ad9d3" xlink:to="loc_srt_ProductOrServiceAxis_83000482-fcaa-472a-baeb-681ebe60573d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_83000482-fcaa-472a-baeb-681ebe60573d_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_83000482-fcaa-472a-baeb-681ebe60573d" xlink:to="loc_srt_ProductsAndServicesDomain_83000482-fcaa-472a-baeb-681ebe60573d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_58f6817b-f485-4cc6-9688-e8081527ad5a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_83000482-fcaa-472a-baeb-681ebe60573d" xlink:to="loc_srt_ProductsAndServicesDomain_58f6817b-f485-4cc6-9688-e8081527ad5a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ExternalExpensesMember_90c8754f-a281-44e0-a6ac-ceb3b5dd3c97" xlink:href="anab-20250331.xsd#anab_ExternalExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_58f6817b-f485-4cc6-9688-e8081527ad5a" xlink:to="loc_anab_ExternalExpensesMember_90c8754f-a281-44e0-a6ac-ceb3b5dd3c97" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_RosnilimabMember_7b222c28-17fe-4e7b-bc63-19cc9af4563b" xlink:href="anab-20250331.xsd#anab_RosnilimabMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_ExternalExpensesMember_90c8754f-a281-44e0-a6ac-ceb3b5dd3c97" xlink:to="loc_anab_RosnilimabMember_7b222c28-17fe-4e7b-bc63-19cc9af4563b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ANB033Member_4a353a21-4d22-4ec3-ba5a-ae30e9a92770" xlink:href="anab-20250331.xsd#anab_ANB033Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_ExternalExpensesMember_90c8754f-a281-44e0-a6ac-ceb3b5dd3c97" xlink:to="loc_anab_ANB033Member_4a353a21-4d22-4ec3-ba5a-ae30e9a92770" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ANB032Member_a8eba700-9944-4963-b8ff-3e0e922c9e98" xlink:href="anab-20250331.xsd#anab_ANB032Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_ExternalExpensesMember_90c8754f-a281-44e0-a6ac-ceb3b5dd3c97" xlink:to="loc_anab_ANB032Member_a8eba700-9944-4963-b8ff-3e0e922c9e98" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ANB101Member_a79c6db9-1cf8-4d80-afa2-8e99fb0de045" xlink:href="anab-20250331.xsd#anab_ANB101Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_ExternalExpensesMember_90c8754f-a281-44e0-a6ac-ceb3b5dd3c97" xlink:to="loc_anab_ANB101Member_a79c6db9-1cf8-4d80-afa2-8e99fb0de045" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_ImsidolimabMember_4449f55a-2b7a-4999-be55-c7b2e2c1d57a" xlink:href="anab-20250331.xsd#anab_ImsidolimabMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_ExternalExpensesMember_90c8754f-a281-44e0-a6ac-ceb3b5dd3c97" xlink:to="loc_anab_ImsidolimabMember_4449f55a-2b7a-4999-be55-c7b2e2c1d57a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_PreclinicalAndOtherUnallocatedCostsMember_5b872892-57a8-4bfe-ba0f-0b64de0d9ce4" xlink:href="anab-20250331.xsd#anab_PreclinicalAndOtherUnallocatedCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_anab_ExternalExpensesMember_90c8754f-a281-44e0-a6ac-ceb3b5dd3c97" xlink:to="loc_anab_PreclinicalAndOtherUnallocatedCostsMember_5b872892-57a8-4bfe-ba0f-0b64de0d9ce4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_InternalExpensesMember_efe6cbd1-b732-4b4f-9afd-fcef515e6609" xlink:href="anab-20250331.xsd#anab_InternalExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_58f6817b-f485-4cc6-9688-e8081527ad5a" xlink:to="loc_anab_InternalExpensesMember_efe6cbd1-b732-4b4f-9afd-fcef515e6609" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_1c2402cd-1894-4326-aad8-2093b38ebcb1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_def95231-48b2-44f0-b7b6-4fc26b922c3f" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_1c2402cd-1894-4326-aad8-2093b38ebcb1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost_b4ee3fb4-7662-4724-88bb-b2f79f54d32b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_def95231-48b2-44f0-b7b6-4fc26b922c3f" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost_b4ee3fb4-7662-4724-88bb-b2f79f54d32b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_55090a03-f839-4fe4-9957-02a4415d2f4d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_def95231-48b2-44f0-b7b6-4fc26b922c3f" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_55090a03-f839-4fe4-9957-02a4415d2f4d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_6ccb059e-d831-43e2-a4fe-3c20d4f5b497" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_def95231-48b2-44f0-b7b6-4fc26b922c3f" xlink:to="loc_us-gaap_OperatingExpenses_6ccb059e-d831-43e2-a4fe-3c20d4f5b497" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_90b05bab-ae80-4bca-9a73-0c408e57bcc7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_def95231-48b2-44f0-b7b6-4fc26b922c3f" xlink:to="loc_us-gaap_OperatingIncomeLoss_90b05bab-ae80-4bca-9a73-0c408e57bcc7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeOther_8e3e0246-e668-4b27-9186-3c6375f8e6ac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestIncomeOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_def95231-48b2-44f0-b7b6-4fc26b922c3f" xlink:to="loc_us-gaap_InterestIncomeOther_8e3e0246-e668-4b27-9186-3c6375f8e6ac" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_NoncashAdvanceFutureRoyaltiesInterestExpense_22effbf1-8bc3-4cdc-8a69-410f91cb8bb4" xlink:href="anab-20250331.xsd#anab_NoncashAdvanceFutureRoyaltiesInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_def95231-48b2-44f0-b7b6-4fc26b922c3f" xlink:to="loc_anab_NoncashAdvanceFutureRoyaltiesInterestExpense_22effbf1-8bc3-4cdc-8a69-410f91cb8bb4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_a1813705-89b7-417f-91ca-d5e8b981005b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_def95231-48b2-44f0-b7b6-4fc26b922c3f" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_a1813705-89b7-417f-91ca-d5e8b981005b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_6441dc58-50a1-4dbe-b494-3a73489cfa2c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_def95231-48b2-44f0-b7b6-4fc26b922c3f" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_6441dc58-50a1-4dbe-b494-3a73489cfa2c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_54554448-11f1-46e1-8c81-f563cb06c23d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_def95231-48b2-44f0-b7b6-4fc26b922c3f" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_54554448-11f1-46e1-8c81-f563cb06c23d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_5e0ae094-83ca-487e-9033-e43fc031db8c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_def95231-48b2-44f0-b7b6-4fc26b922c3f" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_5e0ae094-83ca-487e-9033-e43fc031db8c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_fe4135b2-9b57-482c-b07e-dea10dc926ad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_def95231-48b2-44f0-b7b6-4fc26b922c3f" xlink:to="loc_us-gaap_NetIncomeLoss_fe4135b2-9b57-482c-b07e-dea10dc926ad" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-roles-2024.xsd#eedm"/>
  <link:definitionLink xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_CollaborationRevenueMember_e5ade3ff-a5fe-498e-abbc-750a7a6eaa7e" xlink:href="anab-20250331.xsd#anab_CollaborationRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain" xlink:to="loc_anab_CollaborationRevenueMember_e5ade3ff-a5fe-498e-abbc-750a7a6eaa7e" xlink:type="arc" order="501"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#IndividualsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#ecd_AllIndividualsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_JohnSchmidMember_a448d4e5-8764-4fe2-bfe2-4e641c22f49f" xlink:href="anab-20250331.xsd#anab_JohnSchmidMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_anab_JohnSchmidMember_a448d4e5-8764-4fe2-bfe2-4e641c22f49f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_DanielFagaMember_28f7dcd0-c361-4187-b9eb-3871dd3a741d" xlink:href="anab-20250331.xsd#anab_DanielFagaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_anab_DanielFagaMember_28f7dcd0-c361-4187-b9eb-3871dd3a741d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_DennisMulroyMember_391d4bf0-c12e-490d-a5ec-9c3e884935b9" xlink:href="anab-20250331.xsd#anab_DennisMulroyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_anab_DennisMulroyMember_391d4bf0-c12e-490d-a5ec-9c3e884935b9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_anab_EricLoumeauMember_04a315cf-b16b-4091-a3d0-585becaaa162" xlink:href="anab-20250331.xsd#anab_EricLoumeauMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_anab_EricLoumeauMember_04a315cf-b16b-4091-a3d0-585becaaa162" xlink:type="arc" order="5"/>
  </link:definitionLink>
</link:linkbase>
