Designing advanced nonprecious metal electrocatalysts to reduce overpotential and accelerate hydrogen evolution reaction (HER) has attracted considerable attention. However, improving the sluggish kinetics for electrocatalytic HER in alkaline media is still a great challenge. Herein, we found that amorphous NiO nanoclusters directly grown on nickel foam (NiO/NF) as a bifunctional HER catalyst demonstrated an ultrahigh electrocatalytic activity in alkaline environment. Such excellent HER performance of NiO/NF might mainly originate from the exposed interfaces of metallic Ni and amorphous NiO. The coordinatively unsaturated amorphous NiO domain is propitious to the adsorption of water molecule and the successive cleavage of HO–H bond, while the neighboring metallic Ni domain is beneficial to the adsorption of resulting Hads intermediate and recombination into hydrogen molecules, thus expediting the HER toward lower overpotential. These findings may open a window to the design and preparation of earth-abundant, low-cost metal oxide/metal electrocatalysts with desirable HER activities.