Three-dimensional (3D) carbon-coated NiCoS nanowires structures doped with nitrogen are used for energy storage and conversions. The nitrogen doping in both the carbon layer and NiCoS nanowires enhances the electrochemical performances. Here, an easily scalable and simple temperature treatment has been used to decorate carbon-coated NiCoS nanowires with nitrogen doping (NC@NiCoS NWs) in 3D carbon architecture (carbon cloth). Benefiting from the nitrogen doping and ultrathin carbon layer, the as-prepared 3D NC@NiCoS NWs electrode exhibits the superior electrochemical performance for both asymmetric supercapacitor and electrocatalytic water splitting. An asymmetric supercapacitor assembled by the NC@NiCoS NWs and active carbon electrodes achieves a high energy density of 1.72 mWh cm (68.87 Wh kg) under a power density of 10.63 mW cm (425 W kg) with 90.1% retention of initial capacitance after 10,000 cycles. When employed as the electrocatalyst, the NC@NiCoS NWs show high activities towards electrocatalytic water splitting.