Abstract: To broaden the range of non-noble metal electrocatalytic materials and address issues such as complex preparation, high cost, and poor electrochemical performance of traditional powder catalysts, a novel non-noble metal antiperovskite, CuNNi₃, was grown on three-dimensional conductive nickel foam (NF), forming a CuNNi₃/NF self-supported electrode. This structural enhancement improves the electrode's conductivity, significantly boosting the reaction rate and stability of electrocatalytic water splitting. Further characterization and analysis of the composition and microstructure of CuNNi₃/NF were conducted, and various electrochemical testing methods were employed to evaluate the material's electrochemical performance. Experimental results indicate that CuNNi₃/NF not only exhibits excellent electrocatalytic activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with overpotentials of only 135 mV and 394 mV at a current density of 10 mA·cm⁻², respectively, but also demonstrates good stability within a chronopotentiometric stability test of 25 hours. The symmetric overall water-splitting device requires only 1.80 V at 10 mA·cm⁻² and maintains a stable operating voltage over long-term operation. These findings indicate that the CuNNi₃/NF self-supported catalyst possesses excellent electrocatalytic performance.