Oxygen vacancy passivation is conducted on BiVO₄ photoanode for selective water oxidation to H₂O₂. The photoelectrochemical impedance spectroscopy suggests that oxygen vacancy passivation facilitates H₂O₂ synthesis by regulating the interfacial charge transfer. Besides, the oxygen vacancy passivation contributes to the stability and prohibits H₂O₂ decomposition, increasing the accumulated H₂O₂ generation.