<SEC-DOCUMENT>0001628280-21-003751.txt : 20210302
<SEC-HEADER>0001628280-21-003751.hdr.sgml : 20210302
<ACCEPTANCE-DATETIME>20210302170340
ACCESSION NUMBER:		0001628280-21-003751
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210226
FILED AS OF DATE:		20210302
DATE AS OF CHANGE:		20210302

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Mastrangelo Joe
		CENTRAL INDEX KEY:			0001833309

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-39291
		FILM NUMBER:		21704912

	MAIL ADDRESS:	
		STREET 1:		199 PIERCE STREET, SUITE 537
		CITY:			FRANKLIN TOWNSHIP
		STATE:			NJ
		ZIP:			08873

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Eos Energy Enterprises, Inc.
		CENTRAL INDEX KEY:			0001805077
		STANDARD INDUSTRIAL CLASSIFICATION:	MISCELLANEOUS ELECTRICAL MACHINERY, EQUIPMENT & SUPPLIES [3690]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		3920 PARK AVENUE
		CITY:			EDISON
		STATE:			NJ
		ZIP:			08820
		BUSINESS PHONE:		(732) 225-8400

	MAIL ADDRESS:	
		STREET 1:		3920 PARK AVENUE
		CITY:			EDISON
		STATE:			NJ
		ZIP:			08820

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	B. Riley Principal Merger Corp. II
		DATE OF NAME CHANGE:	20200227
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_161472257628225.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-02-26</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001805077</issuerCik>
        <issuerName>Eos Energy Enterprises, Inc.</issuerName>
        <issuerTradingSymbol>EOSE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001833309</rptOwnerCik>
            <rptOwnerName>Mastrangelo Joe</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O EOS ENERGY ENTERPRISES, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>3920 PARK AVENUE</rptOwnerStreet2>
            <rptOwnerCity>EDISON</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>08820</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Executive Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2021-02-26</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>750000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>750000.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>750000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock</footnote>
        <footnote id="F2">(2)The reporting person received a grant of RSUs under the Issuer's 2020 Incentive Plan, as amended from time to time, which will vest in three equal installments on each of January 3, 2022, January 2, 2023 and January 1, 2024, subject to continued service through each vesting date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Joe Mastrangelo</signatureName>
        <signatureDate>2021-03-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
