NiSe and NG-NiSe (triethanolamine functionalized and NiSe embedded rGO), as electrode materials for supercapacitor application, were prepared by a hydrothermal technique. XRD confirmed the formation of pure NiSe and NG-NiSe nanocomposites, which showed a hexagonal crystalline structure of NiSe. The structural morphology and particle size of NiSe and NG-NiSe were measured using FESEM and HRTEM analysis, respectively. The oxidation states and elemental compositions of NG-NiSe were investigated by XPS. The electrochemical behaviours of the materials were studied using CV, GCD, and EIS spectra. NG-NiSe showed higher capacitance performance compared to pure NiSe, due to the synergetic effects on the rGO/TEA/NiSe nanocomposite during one-pot synthesis. The energy density and power density of a N-rGO//NG-NiSe asymmetric cell were 28.25 W h kg⁻¹ and 700 W kg⁻¹, respectively.