The commercial production of H2 from water splitting requires highly efficient, low-cost, and stable earth-abundant electrocatalysts to speed up the kinetics of hydrogen evolution reaction (HER). In this study, we proposed a concise and effective strategy for fabricating NiS electrocatalysts on Ni foam (NF) substrate to serve as HER electrocatalysts during potentiostatic electrodeposition. The NiS electrocatalyst shows a cauliflower-like surface morphology when the electrodeposition voltage is adjusted. The proposed electrocatalyst exhibits excellent HER performance with a low overpotential of 58 mV at 10 mA·cm−2 and a small Tafel slope of 81.6 mV·dec−1 in 1.0 M KOH solution. Such a high performance can be attributed to the amorphous phase structures, high conductivity, composition optimization, and the close combination between the electrocatalyst and NF. This study provides a facile, fast, and feasible avenue for developing highly efficient and affordable electrochemical catalysts for HER.