Herein, we demonstrated the controllable fabrication of Bi₂WO₆ nanoplate arrays decorated with Co₃O₄ cocatalysts through the combination of hydrothermal reactions with annealing treatments. The synergistic effect of bulk charge transport and surface oxygen evolution could significantly improve the photoelectrochemical properties (0.45 mA cm⁻², 1.23 V_RHE) for water splitting under simulated solar light, which are much higher than those of traditional Bi₂WO₆ particle photoanodes (0.02 mA cm⁻², 1.23 V_RHE). These demonstrations clearly reveal that the rational construction of a photoanode structure and selective decoration of oxygen evolution cocatalysts could serve as an alternative strategy toward the development of highly efficient water splitting systems.