Abstract: The exploration and development of efficient and low-cost electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are crucial but challenging for addressing the energy crisis and environmental pollution. In this paper, a self-supporting electrode composed of ultrathin ceria and cobalt phosphide nanosheets (CeO₂-CoP/NF) was designed and fabricated on a three-dimensional nickel foam substrate. At 10 mA·cm⁻², the hydrogen evolution overpotential of CeO₂-CoP/NF is 124 mV and 142 mV at 1 mol/L KOH and 0.5 mol/L H₂SO₄, respectively. In addition, CeO₂-CoP/NF can also demonstrate superior OER activity at 100 mA·cm⁻², exhibiting an oxygen evolution overpotential of 328 mV in 1 mol/L KOH, and also has superior cycle stability. The experimental results show that the introduction of CeO₂ can reduce the erosion of the electrolyte and significantly improve the electrochemical performance of the CoP material. This work provides new insights into the development of high-performance electrocatalysts for water splitting.