Photoelectrochemical devices have been developed to enable the conversion of solar energy. However, their commercial potential is restricted by the limited stability of the materials employed. To enhance the stability of photocathode and its solar water splitting performance, a P-Si/TiO₂/HfO₂/MoS₂/Pt composite photocathode is developed in this work. The novel TiO₂/HfO₂/MoS₂ serial nanostructure provides excellent stability of the photocathode, and optimizes the interface energy barrier to further facilitate the transfer process of photogenerated carriers within the photocathode. The best P-Si/TiO₂/HfO₂/MoS₂/Pt photocathode demonstrates an initial potential of 0.5 V (vs. RHE) and a photocurrent density of −29 mA/cm² at 0 V (vs. RHE). Through intensity modulated photocurrent spectroscopy and photoluminescence test, it is known that the enhanced water splitting performance is attributed to the optimized carrier transfer property. These findings provide a feasible strategy for the stability and photon quantum efficiency enhancement of silicon-based photocathode devices.