Significance Oxygen evolution reaction plays a striking role in renewable energy storage and conversion technologies. However, efficient electrocatalysts are necessary to promote this kinetically sluggish reaction. These reported down–top preparation methods of highly efficient transition metal hydroxides usually need delicate control in complex environments, limiting their large-scale application. An iron-oxidizing bacteria corrosion approach is developed to construct iron oxides top–down from iron-oxidizing bacteria corrosion integrated with nickel–iron oxyhydroxides to boost oxygen evolution. This study demonstrates a natural bacterial corrosion strategy to prepare highly efficient electrodes top–down for efficient water oxidation, which may stimulate broad interest in multidisciplinary integration of innovative nanomaterials and emerging technologies.