Vacancies engineering based on semiconductors is an effective method to enhance photoelectrochemical activity. Herein, we used a facile one-step solvothermal method to prepare sulfur vacancies modified ultrathin two-dimensional (2D) ZnIn2S4 nanosheets. The photon-to-current efficiency of sulfur vacancies modified ultrathin 2D ZnIn2S4 nanosheets is 1.82-fold than ZnIn2S4 nanosheets without sulfur vacancies and 2.04-fold than multilayer ZnIn2S4. The better performances can be attributed to the introduced sulfur vacancies in ZnIn2S4, which influence the electronic structure of ZnIn2S4 to absorb more visible light and act as the electrons trapping sites to suppress the recombination of photo-generated carriers. These results provide a new route to designing efficient photocatalyst by introducing sulfur vacancies.