<SEC-DOCUMENT>0000866273-23-000051.txt : 20230905
<SEC-HEADER>0000866273-23-000051.hdr.sgml : 20230905
<ACCEPTANCE-DATETIME>20230905121611
ACCESSION NUMBER:		0000866273-23-000051
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20230828
FILED AS OF DATE:		20230905
DATE AS OF CHANGE:		20230905

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MONTALBANO DOUGLAS J
		CENTRAL INDEX KEY:			0001991888

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-15461
		FILM NUMBER:		231234778

	MAIL ADDRESS:	
		STREET 1:		15 EAST 15TH STREET
		STREET 2:		SUITE 1100
		CITY:			TULSA
		STATE:			OK
		ZIP:			74103

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MATRIX SERVICE CO
		CENTRAL INDEX KEY:			0000866273
		STANDARD INDUSTRIAL CLASSIFICATION:	CONSTRUCTION SPECIAL TRADE CONTRACTORS [1700]
		IRS NUMBER:				731352174
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0630

	BUSINESS ADDRESS:	
		STREET 1:		15 EAST 5TH STREET
		STREET 2:		SUITE 1100
		CITY:			TULSA
		STATE:			OK
		ZIP:			74103
		BUSINESS PHONE:		9188388822

	MAIL ADDRESS:	
		STREET 1:		15 EAST 5TH STREET
		STREET 2:		SUITE 1100
		CITY:			TULSA
		STATE:			OK
		ZIP:			74103
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>wf-form3_169393055709206.xml
<DESCRIPTION>FORM 3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2023-08-28</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000866273</issuerCik>
        <issuerName>MATRIX SERVICE CO</issuerName>
        <issuerTradingSymbol>MTRX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001991888</rptOwnerCik>
            <rptOwnerName>MONTALBANO DOUGLAS J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>15 EAST 5TH STREET</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 1100</rptOwnerStreet2>
            <rptOwnerCity>TULSA</rptOwnerCity>
            <rptOwnerState>OK</rptOwnerState>
            <rptOwnerZipCode>74103</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President, Matrix NAC</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>COMMON STOCK</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>40909</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>RESTRICTED STOCK UNITS</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F4"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2021-08-24</value>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2024-08-24</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>COMMON STOCK</value>
                    <footnoteId id="F1"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1114.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>RESTRICTED STOCK UNITS</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F4"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2022-08-30</value>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <value>2025-08-30</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>COMMON STOCK</value>
                    <footnoteId id="F1"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2421.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>RESTRICTED STOCK UNITS</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F4"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2023-08-30</value>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2026-08-30</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>COMMON STOCK</value>
                    <footnoteId id="F1"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5643.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>RESTRICTED STOCK UNITS</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F4"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2024-08-29</value>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <value>2027-08-29</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>COMMON STOCK</value>
                    <footnoteId id="F1"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>14116.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">MATRIX SERVICE COMPANY COMMON STOCK.</footnote>
        <footnote id="F2">INCLUDES 17,615 SHARES OF MATRIX SERVICE COMPANY COMMON STOCK OWNED OUTRIGHT. THE REMAINING SHARES ARE RESTRICTED STOCK OWNED BUT NOT YET RELEASED DUE TO FUTURE VESTING REQUIREMENTS.</footnote>
        <footnote id="F3">FOR THIS SERVICE-BASED AWARD OF CASH-SETTLED RESTRICTED STOCK UNITS THAT WAS GRANTED ON AUGUST 24, 2020, 25% WILL VEST EACH YEAR FROM AUGUST 24, 2021 TO AUGUST 24, 2024.</footnote>
        <footnote id="F4">EACH RESTRICTED STOCK UNIT IS THE ECONOMIC EQUIVALENT OF ONE SHARE OF MATRIX SERVICE COMPANY COMMON STOCK. ALL RESTRICTED STOCK UNITS ARE SETTLED SOLELY IN CASH WHEN VESTED.</footnote>
        <footnote id="F5">FOR THIS SERVICE-BASED AWARD OF CASH-SETTLED RESTRICTED STOCK UNITS THAT WAS GRANTED ON AUGUST 30, 2021, 25% WILL VEST EACH YEAR FROM AUGUST 30, 2022 TO AUGUST 30, 2025.</footnote>
        <footnote id="F6">FOR THIS SERVICE-BASED AWARD OF CASH-SETTLED RESTRICTED STOCK UNITS THAT WAS GRANTED ON AUGUST 30, 2022, 25% WILL VEST EACH YEAR FROM AUGUST 30, 2023 TO AUGUST 30, 2026.</footnote>
        <footnote id="F7">FOR THIS SERVICE-BASED AWARD OF CASH-SETTLED RESTRICTED STOCK UNITS THAT WAS GRANTED ON AUGUST 29, 2023, 25% WILL VEST EACH YEAR FROM AUGUST 29, 2024 TO AUGUST 29, 2027.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Douglas J. Montalbano</signatureName>
        <signatureDate>2023-09-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
