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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019df40f-17ad-7c27-b37b-54b480d89da0,g:afcfa513-af5d-4bfc-b715-ddc812cebb6d-->
<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.limbachinc.com/role/Cover" xlink:type="simple" xlink:href="lmb-20260505.xsd#Cover"/>
  <link:definitionLink xlink:role="http://www.limbachinc.com/role/Cover" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationTable_019df40f-17ad-7995-a836-c55e682b21f4" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_DocumentInformationTable_019df40f-17ad-7995-a836-c55e682b21f4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressesAddressTypeAxis_019df40f-17ad-7c1e-9ae9-94447e43c4d8" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressesAddressTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_DocumentInformationTable_019df40f-17ad-7995-a836-c55e682b21f4" xlink:to="loc_dei_EntityAddressesAddressTypeAxis_019df40f-17ad-7c1e-9ae9-94447e43c4d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AddressTypeDomain_019df40f-17ad-7c1e-9ae9-94447e43c4d8_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AddressTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_EntityAddressesAddressTypeAxis_019df40f-17ad-7c1e-9ae9-94447e43c4d8" xlink:to="loc_dei_AddressTypeDomain_019df40f-17ad-7c1e-9ae9-94447e43c4d8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AddressTypeDomain_019df40f-17ad-7dd5-a295-199b18b7cb96" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AddressTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_EntityAddressesAddressTypeAxis_019df40f-17ad-7c1e-9ae9-94447e43c4d8" xlink:to="loc_dei_AddressTypeDomain_019df40f-17ad-7dd5-a295-199b18b7cb96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_FormerAddressMember_019df40f-17ad-7569-a082-03cf8866f1a9" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_FormerAddressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_AddressTypeDomain_019df40f-17ad-7dd5-a295-199b18b7cb96" xlink:to="loc_dei_FormerAddressMember_019df40f-17ad-7569-a082-03cf8866f1a9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_019df40f-17ad-7d70-9924-7fe3d50b3f39" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_DocumentType_019df40f-17ad-7d70-9924-7fe3d50b3f39" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_019df40f-17ad-7048-99dc-8ed9b55a42f0" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_DocumentPeriodEndDate_019df40f-17ad-7048-99dc-8ed9b55a42f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_019df40f-17ad-7878-87e8-ec0b088e7e2f" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_EntityRegistrantName_019df40f-17ad-7878-87e8-ec0b088e7e2f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_019df40f-17ad-78b1-899f-fb20226869fc" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_EntityIncorporationStateCountryCode_019df40f-17ad-78b1-899f-fb20226869fc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_019df40f-17ad-7c72-a09c-4b66f7c725ff" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_EntityFileNumber_019df40f-17ad-7c72-a09c-4b66f7c725ff" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_019df40f-17ad-7b6a-9e33-39f7bff793a7" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_EntityTaxIdentificationNumber_019df40f-17ad-7b6a-9e33-39f7bff793a7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_019df40f-17ad-78f4-9a03-d55c791e83c3" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_EntityAddressAddressLine1_019df40f-17ad-78f4-9a03-d55c791e83c3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine2_019df40f-17ad-71f6-8ad5-d015d583ee93" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_EntityAddressAddressLine2_019df40f-17ad-71f6-8ad5-d015d583ee93" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_019df40f-17ad-7308-ae16-e49fd81f1168" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_EntityAddressCityOrTown_019df40f-17ad-7308-ae16-e49fd81f1168" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_019df40f-17ad-7eb4-8333-21d0396b6c07" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_EntityAddressStateOrProvince_019df40f-17ad-7eb4-8333-21d0396b6c07" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_019df40f-17ad-736b-aa63-811c17cb4139" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_EntityAddressPostalZipCode_019df40f-17ad-736b-aa63-811c17cb4139" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_019df40f-17ad-7b66-9b49-9f797e79f0cd" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_CityAreaCode_019df40f-17ad-7b66-9b49-9f797e79f0cd" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_019df40f-17ad-76e5-b1cb-0537c721da52" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_LocalPhoneNumber_019df40f-17ad-76e5-b1cb-0537c721da52" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_WrittenCommunications_019df40f-17ad-785c-aadd-f3c68459f99d" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_WrittenCommunications"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_WrittenCommunications_019df40f-17ad-785c-aadd-f3c68459f99d" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SolicitingMaterial_019df40f-17ad-75ca-8ae5-f433d784d941" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_SolicitingMaterial"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_SolicitingMaterial_019df40f-17ad-75ca-8ae5-f433d784d941" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementTenderOffer_019df40f-17ad-7ab4-a427-1d0cccfbb59b" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_PreCommencementTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_PreCommencementTenderOffer_019df40f-17ad-7ab4-a427-1d0cccfbb59b" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementIssuerTenderOffer_019df40f-17ad-7b17-a98e-079c699066c7" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_PreCommencementIssuerTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_PreCommencementIssuerTenderOffer_019df40f-17ad-7b17-a98e-079c699066c7" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_019df40f-17ad-78db-8c97-e7bb4f976259" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_Security12bTitle_019df40f-17ad-78db-8c97-e7bb4f976259" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_019df40f-17ad-7235-a000-287c7c899937" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_TradingSymbol_019df40f-17ad-7235-a000-287c7c899937" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_019df40f-17ad-7f87-8a72-5d02dcf36138" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_SecurityExchangeName_019df40f-17ad-7f87-8a72-5d02dcf36138" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_019df40f-17ad-73f4-95c4-ebc0f0ad1853" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_EntityEmergingGrowthCompany_019df40f-17ad-73f4-95c4-ebc0f0ad1853" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_019df40f-17ad-72b4-a2a5-d6e50be28d1e" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_AmendmentFlag_019df40f-17ad-72b4-a2a5-d6e50be28d1e" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_019df40f-17ad-73b1-8367-3c5756f81433" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019df40f-17ad-7b82-8ea1-aefca5b3f5fa" xlink:to="loc_dei_EntityCentralIndexKey_019df40f-17ad-73b1-8367-3c5756f81433" xlink:type="arc" order="22"/>
  </link:definitionLink>
</link:linkbase>
