The sluggish kinetics of electrocatalysts in the alkaline hydrogen evolution reaction (HER) is a critical challenge to attain efficient progress in water electrolysis for carbon-neutral hydrogen production. Here, we present a high-performance and durable heterostructure of NiMo/CoMoO₄ for the alkaline HER constructed via a two-pot in situ growth strategy on a nickel foam (NF). The density of active sites and the surface area of the hybrid catalyst augmented almost three-fold compared to those of pristine CoMoO₄. The heterostructure composed of metallic NiMo and oxygen vacancy (O_v)-confined CoMoO₄ facilitated the H adsorption on the metallic side and OH adsorption on the oxide side. The hierarchical hybrid catalyst on NF featured a low overpotential of 102 mV at 10 mA cm^–2, approaching that of platinum on carbon (83 mV) in 1.0 M KOH. The turnover frequency of 0.012 s^–1 at the overpotential of 100 mV of NiMo/CoMoO₄ is six times higher than that of CoMoO₄, 0.002 s^–1. In addition, the fabricated heterostructure is a highly durable HER catalyst at 30 mA cm^–2 for 30 h. The Faradaic efficiency recorded by a gas chromatograph at 10 and 100 mA cm^–2 revealed nearly 100 and 86–95% hydrogen production efficiency, respectively.