The conversion of renewable biomass offers a great opportunity for economic fabrication of carbon materials for energy storage devices. However, it is difficult to finely tune the structures of biomass-derived hard carbons (BHCs) due to the inherent robust microstructures of biomass itself, limiting the wide applications of BHCs. Obtaining routes to further optimize the structures of BHCs for supercapacitors is still a large challenge. Inspired by nature in which leaves effectively increase the air-accessible surface area of plants to absorb more carbon dioxide for photosynthesis, we aim to increase the accessible surface area of BHCs for ion adsorption by grafting leaf-like units onto the surface of BHCs. In this study, porous carbon nanosheets (PCNSs) functioning as porous leaves are grafted onto rice husk-derived carbons (RHCs) to fabricate PCNS/RHC composites. The as-prepared PCNS/RHC composites are endowed with sheet-like architecture and abundant short pores. As the electrodes for supercapacitors, the PCNS/RHC composite exhibits a high specific capacitance of 315 F g−1 at 0.1 A g−1 and an excellent rate capability of 189 F g−1 at 50 A g−1. The present study demonstrates an effective and universal strategy to boost the functionality of BHCs materials for energy storage devices.