Although hydrogen gas (H2) storage might enable offshore renewable energy to be stored at scale, the commercialization of technology for H2 generation by seawater electrolysis depends upon the development of methods that avoid the severe corrosion of anodes by chloride (Cl−) ions. Here, it is revealed that the stability of an anode used for seawater splitting can be increased by more than an order of magnitude by loading Ag nanoparticles on the catalyst surface. In experiments, an optimized NiFe-layered double hydroxide (LDH)@Ag electrode displays stable operation at 400 mA cm−2 in alkaline saline electrolyte and seawater for over 5000 and 2500 h, respectively. The impressive long-term durability is more than 20 times that of an unmodified NiFe-LDH anode. Meticulous characterization and simulation reveals that in the presence of an applied electric field, free Cl− ions react with oxidized Ag nanoparticles to form stable AgCl species, giving rise to the formation of a Cl−-free layer near the anode surface. Because of its simplicity and effectiveness, it is anticipated that the proposed strategy to immobilize chloride ions on the surface of an anode has the potential to become a crucial technology to control corrosion during large-scale electrolysis of seawater to produce hydrogen.