The electrochemical properties exhibited by the zinc-doped alumina nanoparticles suggest their potential as another viable alternative for supercapacitor electrode applications. The strategic placement of Zn2+ ions within the interstices of the alumina lattice forms potential barriers between Al3+ and Zn2+ ions, acting as effective centers for trapping charges. The structural changes report a decrease in the average crystallite size from 9 to 5 nm. The formation of trapping centers is confirmed by the enhancement in optical band gap value from 1.89 to 4.21 eV. The XPS data confirms the oxidation state of + 3 and + 2 for Al and Zn ions, respectively. A prolonged charge retention and an increased energy storage density are evidenced by the observed value of 1237 F g–1 at 1 A g–1. Furthermore, the stability of alumina gets enhanced on doping, demonstrating for the first time an impressive 92% stability over 10,000 cycles. The 5% Zn-doped Al2O3 electrode has the highest diffusion coefficient of 8.9 × 10–12 cm2 s–1, showing efficient active sites for electrolyte ion intercalation. The asymmetric supercapacitor device analysis with 5% Zn-doped alumina as one of the electrodes attains a stability of 85% after 5000 repeated cycles. The device achieves a better energy density value of 47.63 W h kg–1 at a power delivery rate of 996.9 W kg–1. This study offers valuable insights into the electrochemical performance of zinc-doped alumina nanoparticles, underscoring their potential for high-performance energy storage applications in supercapacitor devices.