Uniting the advantages of molecular and heterogeneous catalysts, a continuing effort in heterogeneous catalysis, has often proved to be challenging. This work introduces a facile strategy to obtain molybdenum-oxo functional groups strongly anchored on metallic copper support through in situ electrochemical reduction of a cuprous oxomolybdate thin film resulting from electroless plating. The oxomolybdate modified copper electrode exhibits enzyme-like activity and excellent stability for the hydrogen evolution reaction over the entire pH range, together with excellent mechanical properties and cost effectiveness that are needed for commercial applications, including seawater electrolysis. In situ Fourier transformed ac voltammetric study revealed two underlying Mo-IV/IIII and Mo-III/II processes that are responsible for the high catalytic activity of the material. This study opens up a new avenue for designing advanced heterogeneous catalysts for a greener future using a broad range of oxometalates.