AbstractAn efficient and cost-effective oxygen evolution reaction (OER) electrocatalyst is key for electrochemical energy generation and storage technologies. Here, the rational design and in situ formation of an antiperovskite-based hybrid with a porous conductive Cu_1−xNNi_3−y (x and y represent defect) core and amorphous FeNiCu (oxy)hydroxide shell is reported as a promising water oxidation electrocatalyst, showing outstanding performance. Benefiting from the unique advantage of core–shell structure, as well as the synergistic effect of Fe, Ni, and Cu and the highly porous hierarchical structure, the hybrid catalyst exhibits highly efficient and robust OER performance in alkaline environments, outperforming the benchmark IrO₂ catalyst in several aspects. Our findings demonstrate the application potential of antiperovskite-based materials in the field of electrocatalysis, which may inspire insights into the development of novel materials for energy generation and storage applications.