In this work, a water splitting photoanode composed of a BiVO 4 thin film surface modified by the deposition of a rhodium (Rh)-doped SrTiO 3 perovskite is fabricated, and the Rh-doped SrTiO 3 outer layer exhibits special photoelectrochemical (PEC) oxygen evolution co-catalytic activity. Controlled intensity modulated photo-current spectroscopy, electrochemical impedance spectroscopy, and other electrochemical results indicate that the Rh on the perovskite provide an oxidation active site during the PEC water oxidation process by reducing the reaction energy barrier for water oxidation. Theoretical calculations indicate that the water oxidation reaction is more likely to occur on the (110) crystal plane of Rh-SrTiO 3 because the oxygen evolution reaction overpotential on the (110) crystal plane is reduced significantly. Therefore, the obtained BiVO 4 /Rh5%-SrTiO 3 photoanode exhibits an optimized PEC performance. In particular, it facilitates the saturation of the photocurrent density. Thus, the presence of doped Rh in SrTiO 3 can reduce the amount of noble metals required while achieving excellent and stable oxygen evolution properties.