Display omitted •Loofah sponge-derived 3D porous activated carbon is facilely prepared.•Hierarchical pores are constructed in the resulting SAC-x architecture.•SAC-4 exhibits excellent capacity performance in the three- and two-electrode systems.•The resulting materials have tremendous potentials for the energy storage applications. Biomass carbon source is generally cheap, environmentally friendly and readily available in high quality and quantity. In this work, a series of loofah sponge-derived activated carbon (SAC-x) with hierarchical porous structures are prepared by KOH chemical activation and used as electrode materials for supercapacitors. The pore size can be easily controllable by changing the dosage of KOH. The optimized material (SAC-4) exhibits a high specific capacitance of 309.6Fg−1 at 1Ag−1 in the three-electrode system using 6M KOH electrolyte. More importantly, the as-assembled symmetric supercapacitor based on SAC-4 exhibits a high energy density of 16.1Whkg−1 at a power density of 160.0Wkg−1 using 1M Na2SO4 electrolyte. These remarkable results demonstrate the exciting commercial potential of SAC-x for high-performance supercapacitor applications due to their high specific surface area, appropriately porous structure, and the trace heteroatom (O and N) functionalities.