The enhanced separation and injection efficiencies of photogenerated carriers is essential to improve the photoelectrochemical (PEC) performance of WO3 photoanode. In this work, we firstly synthesized WO3/NiCo2O4 heterojunction through simple hydrothermal‐annealing method as well as investigate the effect and mechanism of NiCo2O4 on WO3 for PEC performances. The measurements demonstrate that the nano‐needle NiCo2O4 grown on the surface of WO3 induces the bimetallic Ni/Co redox reaction sites extensively exposed to the electrolyte, which is beneficial to enhance the PEC performances of WO3 photoanode, such as photocurrent density improved by four times (0.84 mA/cm2 at 1.23 V vs. RHE) as well as more negative initial potential (∼280 mV) in contrast to bare WO3. Further investigation shows the remarkable enhancement of PEC performances is attributed to improved surface reaction kinetics, the enhanced injection efficiency and separation efficiency of photogenerated carriers due to the co‐catalyst effect of NiCo2O4 and the formation of WO3/NiCo2O4 heterojunction. This work provides reference for application of heterojunction with co‐catalyst function, which is beneficial to the development and application of similar structures.