The development of hybrid nanostructured electrodes has emerged as an effective approach to address the inherent limitations of individual electrode materials in supercapacitors. Hybrid nanocomposites integrating ZnGa2O4 with graphitic carbon nitride (g-CN) are developed to enhance the electrochemical performance of supercapacitor electrodes. Comprehensive structural and surface characterizations (XRD, FT-IR, FE-SEM, TEM, XPS and BET) elucidate the phase purity, crystallinity, functional groups, surface morphology, oxidation states and porosity of the synthesized materials, which thereby confirms the successful integration of g-CN with ZnGa2O4 in the prepared materials. Electrochemical studies infer that the fabricated g-CN@ZnGa2O4 (1.5:1) electrode delivers the highest specific capacitance of about 594.0 F g−1, significantly outperforming ZnGa2O4 and g-CN@ZnGa2O4 (1:1) electrodes. This enhanced charge-storage behaviour is due to reduced charge-transfer resistance, improved electronic transport, and facilitated ion diffusion arising from effective interfacial interaction between ZnGa2O4 and g-CN. Furthermore, the asymmetric supercapacitor device assembled using the fabricated g-CN@ZnGa2O4 (1.5:1) electrode delivers specific capacitance of about 85.33 F g−1 with excellent cyclic stability, retaining 69.0% of its initial capacitance after 5000 charge–discharge cycles at 5 A g−1. It also exhibits coulombic efficiency of about 96.0%, energy and power densities of about 26.66 Wh kg−1 and 750.0 W kg−1 respectively. These results demonstrate that g-CN incorporation represents an effective strategy for engineering ZnGa2O4-based composite electrodes with enhanced charge storage capability, positioning the developed materials as promising candidates for advanced supercapacitor systems.