Fe-Mn oxides exhibit significant potential in the application of chemical and electrochemical remediation of groundwater arsenic contamination. However, the mechanism controlling the equilibrium between chemisorption inhibition and capacitive adsorption enhancement at ferromanganese oxide electrodes is unclear, posing significant challenges to achieving both electrochemical arsenic removal efficiency and cycle stability. Here, we introduce for the first time a defect engineering strategy to synthesize defect-rich, reduced graphene oxide-anchored MnFe