With the increase of energy shortage and environmental pollution, it is critical to develop economic approaches to synthesize materials and fabricate devices for energy conversion and storage. In this study, we explored to synthesize Co₃O₄ supported porous carbon derived from biomass as electrode materials for supercapacitors. It is cost saving to obtain carbon materials with a porous structure and large surface area from biomass. The special structure of biomass carbon is beneficial for the deposition of functional nanoparticles and improvement in the supercapacitance. In this work, a simple method was applied to carbonize and activate alkali-treated wheat flour, and porous carbon with three-dimensional network structure was obtained. The porous carbon electrode exhibits a high specific capacitance of 185 F·g^-1 at 0.5 A·g^-1 in 2M KOH. Furthermore, Co₃O₄ supported porous carbon with excellent supercapacitance was synthesized. The results show that metal oxide supported biomass porous carbon has great potential application as electrode materials of supercapacitors.