Clean and renewable energy resources are the present and future of the global energy demand. Water-to-hydrogen production by electrochemical and photocatalytic methods using solar, wind, and other renewable energy resources is the finest technology to produce green hydrogen. The choice of electrocatalyst and photocatalyst is important for the development of the next-generation water-splitting system. Metal sulfide (MS) is exclusively explored as an active catalyst for electrochemical as well as photocatalytic hydrogen evolution reactions (HER). The overall intrinsic catalytic activity of the MS depends on the microstructure, composition, heterojunction, bandgap energy, and surface chemical state. For example, microstructure to surface chemical structure offered huge opportunities to stimulate the catalytic efficiency of MS-based catalysts. However, the synthesis protocol and surface interface to performance correlation need to be analyzed thoroughly to rationalize the efficiency of the catalyst. Therefore, careful evolution is needed to evaluate the performance of the MS-based catalyst for HER. The chapter is aimed to provide thoughtful information on the MS-based catalyst synthesis methods, structure, composition to electrochemical and photocatalytic performance relation, and durability for water-to-H2 production efficiency.