The oxygen evolution reaction (OER) is integral to the production of green hydrogen via seawater electrolysis. However, it faces significant challenges, including suboptimal catalytic activity, pronounced corrosion induced by Cl− ions, and restricted operational lifetimes. In this study, a heterostructured hybrid catalyst composed of an amorphous NiFe-layered double hydroxide (LDH) and a crystalline NiMoO₄ is presented. Leveraging the synergistic coupling interactions, the NiFe-LDH/NiMoO₄ demonstrates a remarkable OER performance in seawater electrolysis, requiring a minimal overpotential of merely 339 mV to attain an industrial-level current density of 500 mA cm−2. Experimental findings reveal that the constructed NiFe-LDH/NiMoO₄ architecture significantly enhances electron transfer between the Ni and Fe sites, resulting in the formation of high-valent Ni species that are beneficial for OER catalysis. A mechanistic analysis elucidates the phenomenon whereby the integration of NiFe-LDH and NiMoO₄ mitigates Cl− ions corrosion and optimizes the adsorption of vital oxygen-containing intermediates, accelerating the kinetics of alkaline seawater OER and improving catalytic performance during the seawater electrolysis process.