Photocatalytic H₂ evolution has been proven as one of the promising strategies for addressing global energy and environmental issues. Herein, a binary Z-scheme heterostructure of a WO₃/ZnIn₂S₄ photocatalyst was artificially constructed through a simple hydrothermal method. A variety of characterization tests were employed to prove the effective coupling of WO₃ nanoparticles and ZnIn₂S₄ particles for the fabrication of the WO₃/ZnIn₂S₄ heterostructure. It was found that the decoration of WO₃ nanoparticles could significantly promote the photocatalytic H₂ evolution activity of ZnIn₂S₄ under visible-light irradiation, and the H₂ evolution rate of 5 wt% WO₃/ZnIn₂S₄ composite could reach 1945.88 μmol h⁻¹ g⁻¹, which was 7.9 times that of pristine ZnIn₂S₄ and could rival that of previously reported ZnIn₂S₄-based photocatalysts. On the basis of photoelectrochemical results, the direct Z-scheme heterojunction rather than the type-II heterojunction was proposed to explain the significantly enhanced photocatalytic performance of the WO₃/ZnIn₂S₄ photocatalyst. The enhancement of photocatalytic activity could be attributed to the efficient Z-direction charge transfer at the WO₃/ZnIn₂S₄ heterostructure interface, thus reducing the recombination rate of the photogenerated carriers of the system. This work provides new insights into the construction of direct Z-scheme heterostructured ZnIn₂S₄-based photocatalysts for highly efficient photocatalytic H₂ evolution.