dvancing the design of nanoparticles and their composites with optimized structural and surface characteristics offers broad prospects for multi-domain applications. In this regard, pure NiGa2O4 and 75% and 85% g-C3N4@NiGa2O4 nanocomposites were successfully synthesized via the hydrothermal method. Structural analysis and phase verification of the samples were carried out using X-ray diffraction and Raman spectroscopy, while the elemental composition along with its valence state was investigated using XPS analysis. The morphological changes induced by the incorporation of graphitic carbon nitride (g-C3N4) was analyzed using scanning electron microscopy (SEM). Electrochemical evaluation showed that the 85% g-C3N4@ NiGa2O4 nanocomposite exhibited superior capacitive performance, delivering high specific capacitance of 259.6 Fg−1 at 1 Ag−1 of current density. Furthermore, the asymmetric supercapacitor (ASC) system based on the optimized composite demonstrated enhanced energy storage performance, achieving a notable energy density of 24.2 Whkg−1 and power density of 750 Wkg−1. The enhanced electrochemical performance of the nanocomposite arises from the synergistic interplay between g-C3N4 and NiGa2O4, as well as its optimized morphology, which supports efficient charge transport and storage. These findings offer insights on the systematic design of nanocomposites combining graphitic carbon nitride with mixed metal oxides, enabling future innovations in hybrid supercapacitor devices.