<SEC-DOCUMENT>0001576280-24-000210.txt : 20240910
<SEC-HEADER>0001576280-24-000210.hdr.sgml : 20240910
<ACCEPTANCE-DATETIME>20240910170137
ACCESSION NUMBER:		0001576280-24-000210
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20240909
FILED AS OF DATE:		20240910
DATE AS OF CHANGE:		20240910

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Saia John G.
		CENTRAL INDEX KEY:			0001737840
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38683
		FILM NUMBER:		241290718

	MAIL ADDRESS:	
		STREET 1:		3100 HANOVER STREET
		CITY:			PALO ALTO
		STATE:			CA
		ZIP:			94304

	FORMER NAME:	
		FORMER CONFORMED NAME:	Saia John
		DATE OF NAME CHANGE:	20180417

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Guardant Health, Inc.
		CENTRAL INDEX KEY:			0001576280
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-MEDICAL LABORATORIES [8071]
		ORGANIZATION NAME:           	08 Industrial Applications and Services
		IRS NUMBER:				454139254
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		3100 HANOVER STREET
		CITY:			PALO ALTO
		STATE:			CA
		ZIP:			94304
		BUSINESS PHONE:		855-698-8887

	MAIL ADDRESS:	
		STREET 1:		3100 HANOVER STREET
		CITY:			PALO ALTO
		STATE:			CA
		ZIP:			94304
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wk-form4_1726002091.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2024-09-09</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001576280</issuerCik>
        <issuerName>Guardant Health, Inc.</issuerName>
        <issuerTradingSymbol>GH</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001737840</rptOwnerCik>
            <rptOwnerName>Saia John G.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>3100 HANOVER STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>PALO ALTO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94304</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Legal Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2024-09-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>443</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>23.77</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>28729</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">These shares were retained by the Company in order to meet the tax withholding obligations of the award-holder in connection with the vesting of an installment of the restricted stock units. The amount retained by the Company was not in excess of the amount of the tax liability.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ John G. Saia</signatureName>
        <signatureDate>2024-09-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
