In conclusion, MoO₃-restricted CoMo-LDH exhibits excellent OER activity and stability in seawater electrolysis. The regulation of the interface by this ultrathin MoO₃ layer promotes the formation of CoMo-LDH as the highly active phase. Furthermore, the in-situ formation of the MoO₃ layer plays a crucial role in shielding Cl from the catalytic active interface, decelerating the corrosion rate of the catalyst. Collectively, this study not only developed a potent and stable catalyst for leveraging vast seawater resources in substantial hydrogen production but also revealed a mechanism for constrained dynamic surface reconstruction, thus providing valuable insights for designing efficient and robust LDH-type catalysts.