The efficient utilization of biomass waste has always been a top priority for human sustainable development and a key to achieving Carbon Neutrality. In this work, KMnO4 was used as a template and activator, on the premise of optimizing the carbonization time and activator concentration, fungus bran was converted into hierarchical porous carbon by adjusting the carbonization temperature. The results show that the fungus bran-derived carbon (FBC) can retain heteroatoms and a hierarchical porous structure was constructed. In 6 M KOH aqueous electrolyte, the capacitance of the best-performed FBC reached 333 F g-1 at a current density of 0.5 A g-1. Ultimately, the symmetric supercapacitor assembled with FBCs holds a power density of 250 W kg-1 at the energy density of 6.09 Wh kg-1. This work testifies the practicality of the application of fungus bran to energy storage devices and provides a new insight for the efficient utilization of biomass waste.