Efficient solar-powered water oxidation over BiVO4-based anodes requires coupling photoactive semiconductors to improve inferior activity and stability. Herein, we examine how functionalization with coated tungsten trioxide WO3 affects the photoelectrocatalytic performance of TaON-BiVO4 photoanodes prepared by the doctor-blade method. The effects of the formation of the particularly-porous microstructure and PEC performance of the resulting anodes are explored. Significant enhancements were achieved in water oxidation photocurrent densities at 1.23 V (vs. RHE) with the use of TaON-BiVO4/WO3 photoanodes compared to unmodified TaON-BiVO4. All the composites and photoanodes were studied via numerous characterization methods. Besides, the formation process and probable transfer mechanism of photoinduced carriers were also investigated in detail.