AbstractDirectional organic transformation via a green, sustainable catalytic reaction has attracted a lot of attention. Herein, we report a photoelectrochemical approach for highly selective epoxidation of alkenes in a salt solution using Co2(OH)3Cl (CoOCl) as a bridge of photo‐generated charge, where the lattice Cl− of CoOCl can be oxidized to generate HClO by the photo‐generated holes of BiVO4 photoanode and be spontaneously recovered by Cl− of a salt solution, which then oxidizes the alkenes into the corresponding epoxides. As a result, a series of water‐soluble alkenes, including 4‐vinylbenzenesulfonic acid sodium, 2‐methyl‐2‐propene‐1‐sulfonic acid sodium, and 3‐methyl‐3‐buten‐1‐ol can be epoxidized with near 100 % conversion rate and selectivity. Through further inserting a MoOx protection layer between BiVO4 and CoOCl, the stability of CoOCl−MoOx/BiVO4 can be maintained for at least 120 hours. This work opens an avenue for solar‐driven organic epoxidation with a possibility of on‐site reaction around the abundant ocean.