Both bulk charge separation and surface reaction kinetics are highly important to semiconductor-based water splitting photoanodes. Polyaniline (PANI) with dual functions of hole transport and photothermal conversion is introduced to construct PANI/BiVO₄ composite photoanodes. On the one hand, bulk charge separation is enhanced due to the formation of a p–n heterojunction. On the other hand, the charge separation efficiency is further improved because of the temperature elevation induced by the photothermal effect of PANI. In addition, cobalt phosphate (Co-Pi) as a cocatalyst is introduced to accelerate the surface water oxidation reaction, which is also further promoted via the photothermal effect of PANI. Assisted by NIR light, the resultant Co-Pi/PANI/BiVO₄ photoanode achieves a remarkable water oxidation photocurrent of 4.05 mA cm⁻² at 1.23 V_RHE (V vs. the reversible hydrogen electrode), over 300% higher than that of the pristine BiVO₄ photoanode. The introduction of the photothermal effect can be extended to improve the PEC performance of other photoelectrodes, such as Fe₂O₃, WO₃ and TiO₂.