Cobalt-based materials are considered to be promising electrocatalysts for the oxygen evolution reaction (OER). However, their catalytic efficiencies are still limited by sluggish surface adsorption and high activation overpotentials. Herein, Lewis acid Mg2+-doped Co3(PO4)2 nanosheets were prepared through a simple two-step strategy for enhanced electrocatalytic oxygen evolution reaction. The Lewis acid Mg2+ dopants can increase the cobalt-oxygen covalency and thus facilitate the adsorption of oxygenated intermediates, charge transfer and the pre-oxidation of cobalt species during the OER.