Electrochemical water splitting is one of the promising energy-conversion technologies to utilize intermittent renewable energy and produce hydrogen for clean energy. Pyrite-type transition-metal dichalcogenides have great potential to be applied for energy conversion. This article reviews recent progress in the performance of pyrite-type nanomaterials on the hydrogen evolution reaction, including an overview of crystal and electronic structure of pyrites and the principles of improving electrocatalytic activity and stability for S-based, Se-based, ternary, and other pyrites.