Biomaterials play a significant role in energy storage devices owing to their renewable, inexpensive and eco-friendly peculiarity. In this study, potato biomass porous carbon (PBPC), which was fabricated by a facile two-step carbonization, was used as the anode material for potassium-ion batteries (KIBs). The crystal structure and mesoporous morphology of the carbon derivative at various carbonation temperatures are fully investigated. The electrochemical performance of PBPC electrodes is evaluated, presenting a high reversible specific capacity (248 mA h g−1 at 100 mA g−1), an excellent rate performance (152 mA h g−1 at 1000 mA g−1) and a superior cycle stability (almost no capacity decay after 400 cycles at a current density of 500 mA g−1 with a Coulombic efficiency about 100%). The superior electrochemical performance is mainly attributed to the uniformly distributed mesopores on PBPC electrode which facilitate the electrolyte transportation and diffusion. This work provides a simple and novel strategy to construct porous carbon as high-performance anode materials for KIBs through a sustainable and environment-friendly way.