Cross-coupling between two similar or identical functional groups to form a new C–C bond is a powerful tool to rapidly assemble complex molecules from readily available building units, as seen with olefin cross-metathesis or various types of cross-electrophile couplings1,2 The Kolbe electrolysis involves the oxidative electrochemical decarboxylation of alkyl carboxylic acids to their corresponding radical species followed by recombination to generate a new C–C bond3–12 As one of the oldest known Csp3–Csp3 bond forming reactions, it holds incredible promise for organic synthesis, yet its use has been near non-existent. From the perspective of synthesis design, this transformation could allow one to couple the most available carboxylates without regard to polarity or neighbouring functionality13 In practice, this promise is undermined by the strongly oxidative electrolytic protocol employed traditionally since the 19th century5 thereby severely limiting its scope. Here, we show how a mildly reductive Ni-electrocatalytic system can couple two different carboxylates via in situ generated redox-active esters (RAEs), termed doubly decarboxylative cross-coupling (dDCC). This operationally simple methodcan be used to heterocouple primary, secondary and even certain tertiary RAEs, thereby opening up a powerful new approach for synthesis. The reaction, which cannot be mimicked using stoichiometric metal reductants or photochemical conditions, tolerates a range of functional groups, is scalable, and is used for the synthesis of 32 known compounds, reducing overall step-counts by 73%.