The　pursuit　of　sustainable　energy　utilization　arouses　increasing　interest　in　efficiently　producing　durable　battery　materials　and　catalysts　with　minimum　environmental　impact.　As　green,　safe,　and　cheap　eutectic　mixtures,　deep　eutectic　solvents　(DESs)　provide　tremendous　opportunities　and　open　up　attractive　perspectives　as　charge　transfer　and　reaction　media　for　electrochemical　energy　storage　and　conversion　(EESC).　In　this　review,　the　fundamental　properties　of　DESs　are　first　summarized.　Then,　the　important　roles　that　DESs　play　in　various　EESC　technologies　including　advanced　electrolytes　for　batteries/supercapacitors,　media　for　the　preparation　of　electrode　materials　and　catalysts,　and　extracting　agents　for　battery　recycling　are　systematically　reviewed.　A　particular　focus　is　placed　on　the　fundamental　understanding　of　structure–composition–property–performance　relationships.　Finally,　the　challenges　for　the　controllable　design　of　DESs　for　EESC　applications　and　future　developments　are　presented.　This　review　is　expected　to　shed　light　on　developing　advanced　DESs　for　next-generation　EESC　systems.　©　2021　Wiley-VCH　GmbH