Two-dimensional (2D) molybdenum disulfide (MoS2)–based materials are of great interest because of their capacity to efficiently absorb electromagnetic spectrum in the visible region. Starting from the structural and electronic properties, this review discusses the synthesis strategies of 2D MoS2. The major photocatalytic applications of 2D MoS2 such as hydrogen evolution, pollutant degradation, self-cleaning, photoelectrochemical water splitting, and microbial disinfection are summarized. The mechanistic understanding of various photocatalytic applications of 2D MoS2 is summarized through schematic diagrams. In addition, this review outlines the methodologies for improving the 2D MoS2 photocatalysts and recapitulates the research directions in this area of semiconductor photocatalysis.