Use of lithium ion batteries (LIBs) has seen rapid growth in recent years, which requires abundant and low-cost electrode materials. Sweet potato is a worldwide dicotyledonous plant and has usually a high yield. In this work, using sweet potatoes as raw materials, carbon nanoparticles were prepared through a hydrothermal carbonization approach followed by high temperature annealing. We demonstrate that with the as-prepared carbon nanoparticles as anode, the lithium ion battery shows a first discharge capacity as high as 965 mA h g⁻¹ at a current rate of 100 mA g⁻¹. Considering the bio-renewable advantage and facile fabrication procedure, carbon nanoparticles derived from sweet potatoes could sustainably satisfy the increasing need for anode materials for LIBs.