Semiconductor photocatalysis acts as a sustainable green technology to convert solar energy for environmental purification and production of renewable energy. However, the current photocatalysts suffer from inefficient photoabsorption, rapid recombination of photogenerated electrons and holes, and inadequate surface reactive sites. Introduction of oxygen vacancies (OVs) in photocatalysts has been demonstrated to be an efficacious strategy to solve these issues and improve photocatalytic efficiency. This review systematically summarizes the recent progress in the oxygen vacant semiconductor photocatalysts. Firstly, the formation and characterizations of OVs in semiconductor photocatalysts are briefly introduced. Then, highlighted are the roles of OVs in the photocatalytic reactions of three types of typical oxygen‐containing semiconductors, including metal oxides (TiO2, ZnO, WO3, W18O49, MoO3, BiO2‐x, SnO2, etc), hydroxides (In(OH)3, Ln(OH)3 (Ln=La, Pr, and Nd), Layered double hydroxides) and oxysalts (bismuth‐based oxysalts and others) photocatalysts. Moreover, the advanced photocatalytic applications of oxygen vacant semiconductor photocatalysts, such as pollutant removal, H2 production, CO2 reduction, N2 fixation and organic synthesis are systematically summarized. Finally, an overview on the current challenges and a prospective on the future of oxygen vacant materials is proposed. Oxygen vacancies serve as the most effective defect engineering tactic to improve the photoabsorption, charge separation, and surface catalytic capability of photocatalysts. Here, three types of oxygen vacant semiconductors, including metal oxides (TiO2, ZnO, WO3, MoO3, etc), hydroxides (In(OH)3, Ln(OH)3 (Ln=La, Pr, and Nd), layered double hydroxides) and oxysalts (bismuth‐based oxysalts and others) photocatalysts, with diverse photocatalytic applications are summarized.