Photocatalytic hydrogen evolution (PHE) is of great significance to pursue sustainable and clean fuel, however, it remains a great challenge due to the high recombination of photo-generated carriers and low efficiency of surface catalytic activity. Here, we discover the synergistic regulations of both structural and electronic benefits by introducing sulfur vacancies in a 1T-MoS₂ nanosheets host to prompt the transformation of the surrounding 1T-MoS₂ local lattice into a 2H phase, leading to the dramatically enhanced PHE activity. Multiple in situ spectroscopic and microscopic characterizations combined with theoretical calculations demonstrated that in-plane sulfur vacancies as active sites can activate the proton, while the 2H@1T-MoS₂ phase-incorporation can effectively regulate the electronic structure and further improve the conductivity. Therefore, the optimized ZnIn₂S₄@MoS₂ photocatalyst achieves a high PHE activity of 23,233 μmol g⁻¹ with an apparent quantum yield (AQY) of ∼5.09 %. This work provides a new design for improving the photocatalytic activity by synergistically structural and electronic modulations.