Seawater electrolysis for hydrogen (H₂) production has been considered one of the most promising yet challenging strategies to overcome the energy and environmental crises. The ocean can provide infinite hydrogen, which provides 96.5% of the planet’s water reserve, but still there are numerous obstacles that limit the practical application of its electrocatalytic reactions. Despite enormous efforts, poor stability caused by contamination from toxic and corrosive chlorine species, low energy efficiency due to high overpotential and sluggish kinetics of the oxygen evolution reaction (OER) of four electron-proton couple reactions, and the absence of large-scale manufacturing technics for earth-abundant elements based electrocatalysts still unresolved. Recently, many tactics have been proposed to improve energy efficiency, and among them, foreign elements doping and interfacial engineering of electrocatalysts are attracting a lot of attention. In this study, interfacial engineered Fe doped NiS electrocatalyst is designed and fabricated by ball-milling method, which is not only favorable to large-scale fabrication for electrocatalysts, but also improves the electrocatalytic performance by controlling the grain boundary and Fe doping concentration. Synthesized interfacial engineered Fe doped NiS electrocatalyst exhibit high OER performance of 300 mV at a current density of 1000 mA cm^-2. It also shows the high durability for the OER process in seawater. It is expected that this interfacial engineering technic by ball-milling method contributes to sustainable H₂ production industry by designing and mass-producing superior electrocatalytic performance of high durability and low overpotential for seawater splitting.