Designing a facile strategy to access active and atomically dispersed metallic catalysts are highly challenging for single atom catalysts (SACs). Herein, a simple and fast approach is demonstrated to construct Pt catalysts with single atoms in large quantity via ball milling Pt precursor and N‐doped carbon support (K2PtCl4@NC‐M; M denotes ball‐milling). The as‐prepared K2PtCl4@NC‐M only requires a low overpotential of 11 mV and exhibits 17‐fold enhanced mass activity for the electrochemical hydrogen evolution compared to commercial 20 wt% Pt/C. The superior hydrogen evolution reaction (HER) catalytic activity of K2PtCl4@NC‐M can be attributed to the generation of Pt single atoms, which improves the utilization efficiency of Pt atoms and the introduction of Pt‐N2C2 active sites with near‐zero hydrogen adsorption energy. This viable ball milling method is found to be universally applicable to the fabrication of other single metal atoms, for example, rhodium and ruthenium (such as Mt‐N2C2, where Mt denotes single metal atom). This strategy also provides a promising and practical avenue toward large‐scale energy storage and conversion application. A simple and fast approach is developed to construct Pt catalysts with single atoms in large quantity via ball milling a Pt precursor and N‐doped carbon support. The as‐prepared K2PtCl4@NC‐M exhibits 17‐fold‐enhanced mass activity for hydrogen evolution compared to commercial 20 wt% Pt/C.