Three dimensional (3D) Mo-doped nickel sulfide (Ni 3 S 2 ) mesoporous nanostructures on Ni foam were successfully synthesized via the solvothermal method, which showed the superior properties for energy storage and conversion. As an electrode for supercapacitor, 3D Mo-doped Ni 3 S 2 mesoporous nanostructures demonstrated a 604.4 μAh cm -2 specific capacity and good cycling stability. Furthermore, Mo-doped Ni 3 S 2 mesoporous nanostructures exhibited superior hydrogen evolution reaction and oxygen evolution reaction properties and good cycle stability for water splitting. At 1.41 V, the electrolyzer made up of Mo-doped Ni 3 S 2 mesoporous nanostructures reached the 10mA cm -2 catalytic current density, demonstrating outstanding long-term durability. Furthermore, the physical characterization results and mechanism of the 3D Mo-doped Ni 3 S 2 were investigated. Therefore, the study presents the great promise of the 3D Mo-doped Ni 3 S 2 mesoporous nanostructures in energy conversion and storage.