This study presents a novel seawater electrolysis catalyst, Pt-Ni₃N@V₂O₃/NF, which demonstrates exceptional performance in hydrogen production under harsh seawater conditions. The catalyst incorporates a protective V₂O₃ layer to modulate the microcatalytic environment and create in situ dual-active sites consisting of low-loaded Pt and Ni₃N. The V₂O₃ layer acts as an "armor" during electrolysis, significantly reducing the adsorption of Cl⁻ and alkaline earth cations (Ca²⁺ and Mg²⁺) from seawater and preventing corrosion of the active sites on the electrode. The catalyst exhibits an ultralow overpotential of 80 mV at 500 mA cm⁻², a mass activity 30.86 times higher than Pt-C, and maintains performance for at least 500 hours in seawater. The assembled anion exchange membrane water electrolyzers (AEMWE) demonstrate superior activity and durability even under demanding industrial conditions. In situ localized pH analysis elucidates the microcatalytic environmental regulation mechanism of the V₂O₃ layer. Its role as a Lewis acid layer enables the sequestration of excess OH⁻ ions, mitigate Cl⁻ corrosion, and alkaline earth salt precipitation. The catalyst protection strategy by using V₂O₃ presents a promising and cost-effective approach for large-scale sustainable green hydrogen production. The study also highlights the importance of the V₂O₃ layer in enhancing the electronic structure and coordination environment of Pt and Ni₃N, leading to improved catalytic activity and stability. The results demonstrate that the V₂O₃ layer significantly enhances the intrinsic activity of Pt and Ni₃N, and the dual-active site structure contributes to the high catalytic performance. The catalyst shows excellent stability and performance in seawater, with a high hydrogen production rate and near-perfect Faraday efficiency. The study provides insights into the role of the V₂O₃ layer in modulating the local reaction environment and enhancing the catalytic performance of the dual-active site structure. The results suggest that the V₂O₃ layer is essential for the stable performance of the catalyst at high current density. The study also demonstrates the potential of the catalyst for practical applications in seawater electrolysis, with a promising future for cost-effective and environmentally friendly means of producing green hydrogen from seawater.This study presents a novel seawater electrolysis catalyst, Pt-Ni₃N@V₂O₃/NF, which demonstrates exceptional performance in hydrogen production under harsh seawater conditions. The catalyst incorporates a protective V₂O₃ layer to modulate the microcatalytic environment and create in situ dual-active sites consisting of low-loaded Pt and Ni₃N. The V₂O₃ layer acts as an "armor" during electrolysis, significantly reducing the adsorption of Cl⁻ and alkaline earth cations (Ca²⁺ and Mg²⁺) from seawater and preventing corrosion of the active sites on the electrode. The catalyst exhibits an ultralow overpotential of 80 mV at 500 mA cm⁻², a mass activity 30.86 times higher than Pt-C, and maintains performance for at least 500 hours in seawater. The assembled anion exchange membrane water electrolyzers (AEMWE) demonstrate superior activity and durability even under demanding industrial conditions. In situ localized pH analysis elucidates the microcatalytic environmental regulation mechanism of the V₂O₃ layer. Its role as a Lewis acid layer enables the sequestration of excess OH⁻ ions, mitigate Cl⁻ corrosion, and alkaline earth salt precipitation. The catalyst protection strategy by using V₂O₃ presents a promising and cost-effective approach for large-scale sustainable green hydrogen production. The study also highlights the importance of the V₂O₃ layer in enhancing the electronic structure and coordination environment of Pt and Ni₃N, leading to improved catalytic activity and stability. The results demonstrate that the V₂O₃ layer significantly enhances the intrinsic activity of Pt and Ni₃N, and the dual-active site structure contributes to the high catalytic performance. The catalyst shows excellent stability and performance in seawater, with a high hydrogen production rate and near-perfect Faraday efficiency. The study provides insights into the role of the V₂O₃ layer in modulating the local reaction environment and enhancing the catalytic performance of the dual-active site structure. The results suggest that the V₂O₃ layer is essential for the stable performance of the catalyst at high current density. The study also demonstrates the potential of the catalyst for practical applications in seawater electrolysis, with a promising future for cost-effective and environmentally friendly means of producing green hydrogen from seawater.