Alkaline membrane water electrolysis is a promising production technology, and advanced electrocatalyst and membrane electrode design have always been the core technology. Herein, an ion‐exchange method and an environmentally friendly in situ green phosphating strategy are successively employed to fabricate Ru‐Ru₂P heterogeneous nanoparticles by using hydroxyapatite (HAP) as a phosphorus source, which is an exceptionally active electrocatalyst for hydrogen evolution reaction (HER). Density functional theory calculation results reveal that strong electronic redistribution occurs at the heterointerface of Ru‐Ru₂P, which modulates the electronic structure to achieve an optimized hydrogen adsorption strength. The obtained Ru‐Ru₂P possesses excellent HER performance (24 mV at 10 mA cm⁻²) and robust stability (1000 mA cm⁻² for 120 h) in alkaline media. Furthermore, an environmentally friendly membrane electrode with a sandwich structure is assembled by HAP nanowires as an alkaline membrane, Ru‐Ru₂P as a cathodic catalyst, and NiFe‐LDH as an anodic catalyst, respectively. The voltage of (−) Ru‐Ru₂P || NiFe‐LDH/CNTs (+) (1.53 V at 10 mA cm⁻²) is lower than that of (−) 20 wt% Pt/C || RuO₂ (+) (1.60 V at 10 mA cm⁻²) for overall water splitting. Overall, the studies not only design an efficient catalyst but also provide a new route to achieve a high‐stability electrolyzer for industrial H₂ production.