In the present study, cerium oxide (CeO2) was combined with nickel oxide (NiO) using a microwave-assisted method followed by post-annealing used for supercapacitor applications. The microwave-assisted method enabled rapid and uniform heating, which accelerated reaction kinetics and ensured precise nanostructure formation. Crystallographic and morphological analyses confirmed the formation of nanorod-like structures in the CeO2-NiO nanocomposite without impurities. Electrochemical performance was evaluated using a three-electrode arrangement, revealing a maximum specific capacitance of 975 F g(-)1 at a current density of 2 A g(-)1, along with a low equivalent series resistance. An all-solid-state asymmetric supercapacitor was fabricated using the prepared material as the positive electrode, with activated carbon serving as the negative electrode. This device exhibited an energy density of 12 W h kg(-)1 and a power density of 2000 W kg(-)1, along with excellent cyclic stability, retaining 80% of its initial capacitance after 10,000 charge-discharge cycles. These findings highlight the enhanced electrochemical performance of the CeO2-NiO nanocomposite and its potential for energy storage applications.