With the increasing prominent global environmental issues and the depletion of fossil fuels, the search for renewable energy has become a daunting task. Hydrogen production by water electrolysis, which simultaneously generates hydrogen and oxygen through the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), is an efficient and green hydrogen production method, attracting the interest of an increasing number of researchers. However, currently commercial noble metal catalysts (Pt/C and RuO₂/IrO₂) are expensive and have limited reserves. Therefore, the development of high-performance, low-cost, and highly stable non-noble metal electrocatalysts has become a research hotspot. In this paper, a Ni@Mo₂C/C catalyst with three dimensions (3D) nanosheet structures was successfully prepared via a simple salt-template pyrolysis method. The composition, morphology and structure of Ni@Mo₂C/C material were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The elemental composition and valence states were analyzed using X-ray photoelectron spectroscopy (XPS), and the electrochemical performance of Ni@Mo₂C/C was investigated. The results indicate that at a current density of 10 mA·cm^-2, the overpotentials for the HER and OER of the Ni@Mo₂C/C catalyst are 47 and 232 mV, respectively. In the overall water splitting test, a voltage of only 1.61 V was sufficient to drive a current density of 10 mA·cm^-2, which could be sustained for 100 h.