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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019e92f8-3403-7aea-bd6c-d586b1b66e56,g:e6ca7463-2712-4088-bc5d-cb209c4a5dcf-->
<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://sachemcapital.com/role/Cover" xlink:type="simple" xlink:href="sach-20260604.xsd#Cover"/>
  <link:definitionLink xlink:role="http://sachemcapital.com/role/Cover" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e92f8-3403-7343-aad3-179cfbcd68e9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_us-gaap_StatementTable_019e92f8-3403-7343-aad3-179cfbcd68e9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019e92f8-3403-77ec-b0fd-ae6d8c46d913" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e92f8-3403-7343-aad3-179cfbcd68e9" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019e92f8-3403-77ec-b0fd-ae6d8c46d913" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019e92f8-3403-77ec-b0fd-ae6d8c46d913_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019e92f8-3403-77ec-b0fd-ae6d8c46d913" xlink:to="loc_us-gaap_ClassOfStockDomain_019e92f8-3403-77ec-b0fd-ae6d8c46d913_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019e92f8-3403-7de7-858e-dceb5d18d245" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019e92f8-3403-77ec-b0fd-ae6d8c46d913" xlink:to="loc_us-gaap_ClassOfStockDomain_019e92f8-3403-7de7-858e-dceb5d18d245" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019e92f8-3403-7248-9349-539d9a96999f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e92f8-3403-7de7-858e-dceb5d18d245" xlink:to="loc_us-gaap_CommonStockMember_019e92f8-3403-7248-9349-539d9a96999f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sach_Notes7.75percentDue2025Member_019e92f8-3403-745a-9723-9a37cbde8276" xlink:href="sach-20260604.xsd#sach_Notes7.75percentDue2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e92f8-3403-7de7-858e-dceb5d18d245" xlink:to="loc_sach_Notes7.75percentDue2025Member_019e92f8-3403-745a-9723-9a37cbde8276" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sach_Notes6.00percentDue2026Member_019e92f8-3403-739e-8f4c-a0098672337f" xlink:href="sach-20260604.xsd#sach_Notes6.00percentDue2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e92f8-3403-7de7-858e-dceb5d18d245" xlink:to="loc_sach_Notes6.00percentDue2026Member_019e92f8-3403-739e-8f4c-a0098672337f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sach_Notes6.00percentDue2027Member_019e92f8-3403-7610-8612-11e576050351" xlink:href="sach-20260604.xsd#sach_Notes6.00percentDue2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e92f8-3403-7de7-858e-dceb5d18d245" xlink:to="loc_sach_Notes6.00percentDue2027Member_019e92f8-3403-7610-8612-11e576050351" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sach_Notes7.125PercentDue2027Member_019e92f8-3403-767c-b8cf-9188f50f5829" xlink:href="sach-20260604.xsd#sach_Notes7.125PercentDue2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e92f8-3403-7de7-858e-dceb5d18d245" xlink:to="loc_sach_Notes7.125PercentDue2027Member_019e92f8-3403-767c-b8cf-9188f50f5829" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sach_Notes8.00percentDue2027Member_019e92f8-3403-76ba-aacb-2e6866bb3964" xlink:href="sach-20260604.xsd#sach_Notes8.00percentDue2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e92f8-3403-7de7-858e-dceb5d18d245" xlink:to="loc_sach_Notes8.00percentDue2027Member_019e92f8-3403-76ba-aacb-2e6866bb3964" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_019e92f8-3403-772f-9801-59b50f3593c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e92f8-3403-7de7-858e-dceb5d18d245" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_019e92f8-3403-772f-9801-59b50f3593c3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_019e92f8-3403-7cea-90a0-d0890b9b69f0" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_DocumentType_019e92f8-3403-7cea-90a0-d0890b9b69f0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_019e92f8-3403-7194-9148-fa056a86c361" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_DocumentPeriodEndDate_019e92f8-3403-7194-9148-fa056a86c361" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_019e92f8-3403-7dbf-8947-f90eb8d88491" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_EntityRegistrantName_019e92f8-3403-7dbf-8947-f90eb8d88491" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_019e92f8-3403-7ab4-9c3d-fbea3d95b08a" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_EntityIncorporationStateCountryCode_019e92f8-3403-7ab4-9c3d-fbea3d95b08a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_019e92f8-3403-7ae3-8a90-536a39944057" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_EntityFileNumber_019e92f8-3403-7ae3-8a90-536a39944057" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_019e92f8-3403-7385-8b66-308153be27d2" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_EntityTaxIdentificationNumber_019e92f8-3403-7385-8b66-308153be27d2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_019e92f8-3403-7d92-8728-efa188a6e8d1" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_EntityAddressAddressLine1_019e92f8-3403-7d92-8728-efa188a6e8d1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_019e92f8-3403-7191-94ff-192a25b1000a" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_EntityAddressCityOrTown_019e92f8-3403-7191-94ff-192a25b1000a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_019e92f8-3403-7277-ae91-ebdb2d48351a" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_EntityAddressStateOrProvince_019e92f8-3403-7277-ae91-ebdb2d48351a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_019e92f8-3403-780a-a002-51c334b0a989" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_EntityAddressPostalZipCode_019e92f8-3403-780a-a002-51c334b0a989" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_019e92f8-3403-7c23-882b-9e993f158891" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_CityAreaCode_019e92f8-3403-7c23-882b-9e993f158891" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_019e92f8-3403-7882-914a-3d095e125857" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_LocalPhoneNumber_019e92f8-3403-7882-914a-3d095e125857" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_WrittenCommunications_019e92f8-3403-7143-92e1-388ae4ade5d3" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_WrittenCommunications"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_WrittenCommunications_019e92f8-3403-7143-92e1-388ae4ade5d3" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SolicitingMaterial_019e92f8-3403-7328-aa0c-3e41af2014df" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_SolicitingMaterial"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_SolicitingMaterial_019e92f8-3403-7328-aa0c-3e41af2014df" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementTenderOffer_019e92f8-3403-7d5f-97e2-78e00af9b4e3" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_PreCommencementTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_PreCommencementTenderOffer_019e92f8-3403-7d5f-97e2-78e00af9b4e3" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementIssuerTenderOffer_019e92f8-3403-7d94-b433-110f0a0e8d0d" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_PreCommencementIssuerTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_PreCommencementIssuerTenderOffer_019e92f8-3403-7d94-b433-110f0a0e8d0d" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_019e92f8-3403-7bb3-974d-6937fd4f9a96" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_Security12bTitle_019e92f8-3403-7bb3-974d-6937fd4f9a96" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_019e92f8-3403-7a45-a637-8cb27e725b52" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_TradingSymbol_019e92f8-3403-7a45-a637-8cb27e725b52" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_019e92f8-3403-7b8e-b5c4-6c6fe04c1c61" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_SecurityExchangeName_019e92f8-3403-7b8e-b5c4-6c6fe04c1c61" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_019e92f8-3403-7b87-9804-f1169d60d58a" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_EntityEmergingGrowthCompany_019e92f8-3403-7b87-9804-f1169d60d58a" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_019e92f8-3403-7e21-8e2d-0482510a730a" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_AmendmentFlag_019e92f8-3403-7e21-8e2d-0482510a730a" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_019e92f8-3403-714c-9149-17d0ac23464f" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e92f8-3403-718f-ae18-398386a912e4" xlink:to="loc_dei_EntityCentralIndexKey_019e92f8-3403-714c-9149-17d0ac23464f" xlink:type="arc" order="21"/>
  </link:definitionLink>
</link:linkbase>
