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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2025 Workiva-->
<!--r:1052fb7e-d054-450d-9f14-3883ac9b8b6e,g:dacc3e81-a7bb-4e79-9018-de3ef9bd3563-->
<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/CoverPage" xlink:type="simple" xlink:href="anab-20250603.xsd#CoverPage"/>
  <link:definitionLink xlink:role="http://www.anaptysbio.com/role/CoverPage" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationLineItems_6d5c94cc-ab41-4ae5-b13a-1c6ee9a4df53" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationTable_bd44af43-6837-4e90-a7cb-08e45dcd1f57" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_DocumentInformationLineItems_6d5c94cc-ab41-4ae5-b13a-1c6ee9a4df53" xlink:to="loc_dei_DocumentInformationTable_bd44af43-6837-4e90-a7cb-08e45dcd1f57" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationDocumentAxis_137f1fa1-2dd4-4756-a033-ffba26a3256c" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentInformationDocumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_DocumentInformationTable_bd44af43-6837-4e90-a7cb-08e45dcd1f57" xlink:to="loc_dei_DocumentInformationDocumentAxis_137f1fa1-2dd4-4756-a033-ffba26a3256c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentDomain_137f1fa1-2dd4-4756-a033-ffba26a3256c_default" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_DocumentInformationDocumentAxis_137f1fa1-2dd4-4756-a033-ffba26a3256c" xlink:to="loc_dei_DocumentDomain_137f1fa1-2dd4-4756-a033-ffba26a3256c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentDomain_cbf96bc5-2129-42b8-8ab7-1d1eed5a3ff1" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_DocumentInformationDocumentAxis_137f1fa1-2dd4-4756-a033-ffba26a3256c" xlink:to="loc_dei_DocumentDomain_cbf96bc5-2129-42b8-8ab7-1d1eed5a3ff1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_b86b9294-2799-4b18-bf5e-31ae1882c711" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_6d5c94cc-ab41-4ae5-b13a-1c6ee9a4df53" xlink:to="loc_dei_DocumentType_b86b9294-2799-4b18-bf5e-31ae1882c711" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressesLineItems_bdacaecb-25f2-44c2-9cea-f61119c39bbd" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressesTable_dec2511b-0643-418f-a0e2-625872395391" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_EntityAddressesLineItems_bdacaecb-25f2-44c2-9cea-f61119c39bbd" xlink:to="loc_dei_EntityAddressesTable_dec2511b-0643-418f-a0e2-625872395391" xlink:type="arc" order="2" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressesAddressTypeAxis_726cf1ee-172d-43c9-9840-a18ceea46088" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressesAddressTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_EntityAddressesTable_dec2511b-0643-418f-a0e2-625872395391" xlink:to="loc_dei_EntityAddressesAddressTypeAxis_726cf1ee-172d-43c9-9840-a18ceea46088" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AddressTypeDomain_726cf1ee-172d-43c9-9840-a18ceea46088_default" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_AddressTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_EntityAddressesAddressTypeAxis_726cf1ee-172d-43c9-9840-a18ceea46088" xlink:to="loc_dei_AddressTypeDomain_726cf1ee-172d-43c9-9840-a18ceea46088_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AddressTypeDomain_e4523b49-c2b0-4619-835c-530b4089a561" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_AddressTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_EntityAddressesAddressTypeAxis_726cf1ee-172d-43c9-9840-a18ceea46088" xlink:to="loc_dei_AddressTypeDomain_e4523b49-c2b0-4619-835c-530b4089a561" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_929ed524-7315-4090-870e-8250ab620230" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityAddressesLineItems_bdacaecb-25f2-44c2-9cea-f61119c39bbd" xlink:to="loc_dei_EntityAddressAddressLine1_929ed524-7315-4090-870e-8250ab620230" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine2_0408cbd5-16bb-4cf2-a04f-54fe1c8b03d8" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressAddressLine2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityAddressesLineItems_bdacaecb-25f2-44c2-9cea-f61119c39bbd" xlink:to="loc_dei_EntityAddressAddressLine2_0408cbd5-16bb-4cf2-a04f-54fe1c8b03d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_ebd8f053-0405-47c5-b4e8-a0c03eb7abbf" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityAddressesLineItems_bdacaecb-25f2-44c2-9cea-f61119c39bbd" xlink:to="loc_dei_EntityAddressCityOrTown_ebd8f053-0405-47c5-b4e8-a0c03eb7abbf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_98231ac6-a30f-4932-9d4a-709dd850c4e7" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityAddressesLineItems_bdacaecb-25f2-44c2-9cea-f61119c39bbd" xlink:to="loc_dei_EntityAddressStateOrProvince_98231ac6-a30f-4932-9d4a-709dd850c4e7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_850d16a9-f10c-4a6f-86a1-1be1ee3ab758" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityAddressesLineItems_bdacaecb-25f2-44c2-9cea-f61119c39bbd" xlink:to="loc_dei_EntityAddressPostalZipCode_850d16a9-f10c-4a6f-86a1-1be1ee3ab758" xlink:type="arc" order="4"/>
  </link:definitionLink>
</link:linkbase>
