<p>A systematic approach was adopted to synthesize cobalt hydroxide (Co(OH)₂) blended bismuth oxide (Bi₂O₃) nanocomposites in three different compositions as negative electrodes for supercapacitor applications. The influence of Co(OH)₂ on the structural, morphological, and electrochemical properties of Bi₂O₃ are examined and reported. The pure and Co(OH)₂-included samples fall to the monoclinic structural symmetry, while a higher composition of Co(OH)₂ exhibits fewer native peaks in XRD. The full survey spectrum of XPS confirms the existence of bismuth, cobalt, and oxygen. SEM images show very thin sheet-like morphology, stacked one over the other, which provides higher surface area and facilitates enhanced ion diffusion, which improves the electrochemical properties of the prepared sample. The electrochemical performance of the samples was examined via half-cell configuration for their suitability as negative electrodes in supercapacitor applications. The maximum specific capacity of 984.6 F g⁻¹ is estimated at a specific current of 2 A g⁻¹ for the electrodes consisting of Bi₂O₃ and 5 mole percent of Co(OH)₂, and it is 22.9% higher than the bare Bi₂O₃ electrodes. These efficient nanocomposites exhibit better cycle life by estimating 94% retention at the end of 5000 GCD cycles. The asymmetric supercapacitor device could yield a maximum energy density of 31 Wh kg⁻¹ at a power density of 918 W kg⁻¹. Thus, crafting Bi₂O₃ electrodes by incorporating Co(OH)₂ can be an effective strategy for developing advanced negative electrodes.</p>