A novel CeO2/NiS nanocomposite, combining the advantageous properties of transition metal sulfides (high conductivity) and rare-earth metal oxides (excellent stability), was successfully synthesized using a simple hydrothermal method. This composite leverage synergistic effects to potentially achieve superior electrochemical performance in supercapacitor applications. To evaluate its suitability for supercapacitors, the electrochemical performance of the CeO2/NiS electrode was comprehensively investigated using a series of techniques, including cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) curves, electrochemical impedance spectroscopy (EIS), and cyclic stability analysis. The results demonstrate that the as-prepared CeO2/NiS electrode exhibits significantly improved supercapacitor performance compared to the bare CeO2 electrode. The CV curves of the CeO2/NiS electrode reveal a high specific capacitance of 825.53 F/g at a low scan rate of 5 mV/s, indicating good charge storage capability. Further insights into the charge storage mechanism were obtained using the Trasatti method. This analysis revealed that the total stored capacitance of the CeO₂/NiS electrode is 1250 F/g, with contributions from both outer surface capacitance (94 F/g) and inner diffusion capacitance (1156 F/g). Notably, the dominant contribution (92.5 %) originates from capacitive processes, highlighting the efficient charge storage at the electrode surface. The CeO2/NiS electrode also demonstrates exceptional rate capability, delivering a specific capacitance (Csp) of 710 F/g at a high current density of 1 A/g. Additionally, it exhibits impressive cycling stability, retaining approximately 96.56 % of its initial capacitance even after undergoing 3000 continuous GCD cycles at a high current density of 10 A/g. These results suggest that the CeO2/NiS composite can maintain its performance during extended charge-discharge cycles, a crucial characteristic for practical supercapacitor applications. Finally, an asymmetric supercapacitor device was fabricated using the CeO2/NiS nanocomposite. This device achieved a specific capacitance of 157 F/g, demonstrating the potential of the CeO2/NiS composite for practical energy storage applications.