<SEC-DOCUMENT>0001140361-17-005082.txt : 20170208
<SEC-HEADER>0001140361-17-005082.hdr.sgml : 20170208
<ACCEPTANCE-DATETIME>20170208142706
ACCESSION NUMBER:		0001140361-17-005082
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20170131
FILED AS OF DATE:		20170208
DATE AS OF CHANGE:		20170208

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			UNITED SECURITY BANCSHARES
		CENTRAL INDEX KEY:			0001137547
		STANDARD INDUSTRIAL CLASSIFICATION:	NATIONAL COMMERCIAL BANKS [6021]
		IRS NUMBER:				912112732
		STATE OF INCORPORATION:			CA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2126 INYO STREET
		CITY:			FRESNO
		STATE:			CA
		ZIP:			93721
		BUSINESS PHONE:		5592484930

	MAIL ADDRESS:	
		STREET 1:		2126 INYO STREET
		CITY:			FRESNO
		STATE:			CA
		ZIP:			93721

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MACKOVAK BENJAMIN
		CENTRAL INDEX KEY:			0001697577

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-32897
		FILM NUMBER:		17581999

	MAIL ADDRESS:	
		STREET 1:		2126 INYO STREET
		CITY:			FRESNO
		STATE:			CA
		ZIP:			93721
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2017-01-31</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001137547</issuerCik>
        <issuerName>UNITED SECURITY BANCSHARES</issuerName>
        <issuerTradingSymbol>UBFO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001697577</rptOwnerCik>
            <rptOwnerName>MACKOVAK BENJAMIN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2126 INYO STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>FRESNO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>93721</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>UBFO Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>521120</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By: Strategic Value Investors LP</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Shares owned directly by Strategic Value Investors LP. Mr. Mackovak, solely by virtue of his position as a managing member of Strategic Value Bank Partners LLC, which serves as the general partner of Strategic Value Investors LP, may be deemed to beneficially own the shares owned directly by Strategic Value Investors LP for purposes of Section 16. Mr. Mackovak expressly disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/S/ BENJAMIN MACKOVAK</signatureName>
        <signatureDate>2017-02-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
