Nitrogen-doped porous carbon plates have been prepared by simple and cost-effective pyrolysis carbonization of an easily available biomass-fallen camellia flower and followed by alkali activation. As-prepared nitrogen-doped porous carbon (aNPCP3) possesses a high specific surface area of 2318 m 2  g −1 and abundant micro/meso-pores. As a result, the aNPCP3 samples have been demonstrated to be electrodes for supercapacitors, displaying a high specific capacitance of 354 F g −1 at a current density of 0.2 A g −1 and excellent cycling stability. Further, the aNPCP3 samples used as sulfur host materials for lithium-sulfur batteries exhibit a high capacity of 1210 mAh g −1 and good cycling stability with a small capacity decay of about 0.1 % per cycle. Interestingly, it is found that their electrochemical performances are dependent on their specific surface area, pore structure, and heteroatom-doping content and type of carbon materials to a large extent. Cheapness, convenient resource, and good performance make these electrode materials displaying huge potential in cost-effective high-performance energy storage devices.