Abstract: Developing active and stable ruthenium (Ru)-based electrocatalysts with broad applicability is essential for hydrogen production via overall water splitting. We prepared a series of Ru@VN_1−x catalysts with varying nitrogen vacancy concentrations on vanadium nitride (VN) supports using an impregnation and hydrogen reduction method. Structural characterization indicates that nitrogen vacancies promote the uniform dispersion of Ru nanoparticles and strengthen the metal-support electronic coupling between Ru and VN. Electrochemical tests show that Ru@VN_1−x-m requires overpotentials of only 46 mV and 45 mV to reach 10 mA·cm⁻² in 1 mol·L⁻¹ KOH and 0.5 mol·L⁻¹ H₂SO₄, respectively, operating stably for 60 hours. Alkaline and acidic overall water splitting devices assembled with this catalyst require voltages of 1.54 V and 1.58 V at 10 mA·cm⁻², respectively. These driving voltages are lower than those of commercial RuO₂ electrolyzers. Nitrogen vacancies enhance the interaction between Ru and the defective VN support and regulate the interfacial electronic structure. This optimizes the H* adsorption and desorption behavior, improving the hydrogen evolution reaction (HER) performance across a wide pH range.