<p>The enhancing demands of energy conversion and storage in growing world needs the growth of advanced electrode materials with superior electrochemical and hydrogen evolution performance. The researchers are focused on Ce-doped Co₃O₄ nanomaterials via sol–gel approach for the fulfilment of energy demands and explore sustainable solutions. In this study, pure CeO₂ and CeO₂-doped Co₃O₄ nanomaterials were prepared via sol–gel methodology. The prepared nanomaterials were characterized with various advanced structural and X-ray techniques. The X-ray diffraction analysis of prepared nanomaterial depicted cubic structural with successful incorporation of cerium into cobalt matrix. Moreover, the scanning electron microscope (SEM) analysis of prepared nanomaterial demonstrated refined nano-granules with high porosity and interconnections. The prepared nanomaterials were employed for bi-functional application in supercapacitor and hydrogen evolution reaction performance. The 5% CeO₂-doped Co₃O₄ nanomaterial showed remarkable specific capacitance values about 1097 F/g at 5&#xa0;mV&#xa0;s⁻¹. It showed that the cerium incorporated extra active sites in the metal matrix that enhanced redox reaction activity in the doped nanomaterial. Moreover, the 5% CeO₂-doped Co₃O₄ was also investigated for cyclic stability. The prepared nanomaterial showed 92.64% cyclic stability even after 3000th cycles. Conversely, hydrogen evolution performance of 5% CeO₂-doped Co₃O₄ explored exceptional results. The electrode material depicted over potential value about 232&#xa0;mV, Tafel slope about 96&#xa0;mA dec⁻¹, double layer capacitance values about 26.5 mF cm⁻² and electrochemical active surface area about 662.5 cm² respectively. The HER results ensure that the prepared nanomaterial showed exceptional performance in both supercapacitor and hydrogen evolution reactions. These material open new doors for new researchers in next generation supercapacitor and water splitting performance.</p>