The development of an efficient and affordable bifunctional electrode for full water splitting in basic and neutral conditions is still a challenging issue in obtaining clean and sustainable chemical fuels. Herein, a unique bifunctional electrode consisting of 3D trinary transition-metal phosphide nanosheets with abundant reactive sites anchored on Ni foam, referred to as Fe_xCo_yNi_zP, has been developed through a facile two-step process of electrodeposition and low-temperature phosphidation. When used as a bifunctional electrode for the full water splitting, an applied voltage of 1.57 V is required for a current density of 10 mA cm⁻².