Lattice strain engineering represents a cutting‐edge approach capable of delivering enhanced performance across various applications. The lattice strain can affect the performance of electrochemical catalysts by changing the binding energy between the surface‐active sites and intermediates. In this work, lattice strain is regulated through a homo/heterogeneous atomic interface merging. The strong lattice strain and electronic interactions between Ni and Mo facilitated the reaction kinetic of HER. The prepared NiMo/SSM exhibiting excellent HER catalytic performance with 70 mV overpotential at the current density of 10 mA cm‐2 and long‐term stability. The method of controlling lattice strain through hetero/homo atom interface merging provides a new strategy for designing high‐performance alkaline HER electrocatalysts.