<p>Binary metal oxides have emerged as pSromising materials for advanced electrochemical energy storage systems due to their superior performance characteristics. In this study, we focus on bismuth oxide (Bi₂O₃), a material renowned for its high theoretical capacity, wide potential range, and exceptional power density, as a potential candidate for supercapacitors. Iron doping was employed as a strategy to enhance its electrochemical performance and modulate the band gap, thereby improving conductivity and charge storage efficiency. Fe-doped bismuth oxide (Fe-Bi₂O₃) was synthesized via a solvothermal method with varying iron concentrations (2%, 4%, and 6%), followed by annealing. The pure and iron-doped bismuth oxide samples revealed a combination of monoclinic and cubic phases and a prominent micro-sheet architecture. The introduction of iron doping led to a noticeable reduction in the band gap, highlighting its role in fine-tuning the electronic properties for enhanced energy storage capabilities. The electrochemical evaluation highlighted the 4% Fe-Bi₂O₃ sample as the optimal composition, achieving a remarkable specific capacity of 904 F g⁻¹, a substantial improvement over 101 F g⁻¹ for pristine Bi₂O₃, at 1 A g⁻¹ in a 2&#xa0;M KOH electrolyte. Moreover, this sample exhibited outstanding cyclic stability, retaining 104 F g⁻¹ after 2000 cycles at 10 A g⁻¹.</p> Graphical Abstract <p></p>