Radical reactions play an important role in modern organic synthetic chemistry. The generation of carbon radicals from the homolytic cleavage of carbon–metal bonds has been widely studied as a fundamental step in organometallic chemistry. However, the implementation of this phenomenon in catalysed cascade reactions, that is, an organometallic-radical relay, is a highly challenging undertaking due to transient radicals generated from these thermodynamically disfavoured endergonic processes. Here we disclose a set of catalytic alkene 1,1-difunctionalization reactions conceptually based on an organometallic-radical relay. This strategy enables a diversity of sp3/sp2 fragments and aryl groups to be simultaneously introduced to the same carbon of both terminal and internal alkenes with outstanding chemo- and regioselectivity. This study provides a concept for the generation of functionalized benzylic radicals, which are difficult to access by classical protocols, from non-radical feedstock alkenes and arylboronic acids.