Green and environmentally friendly methods have attracted much attention in the recent research of electrode materials. Natural resources with specific structure and properties are expected to be utilized, and high-performance anodes can be prepared by effectively compounding them with the active components. By choosing kelp with high content of protein as the carbon precursor, a nitrogen-containing MnO/C hybrid with high electrical connectivity has been designed and synthesized. As a kind of seaweed, kelp has an outstanding swelling property in salt solution and its cell membrane is rich in alginate, which is in favor of incorporating and coordinating with Mn2+ to form nanosized MnO particles. Moreover, kelp can be used as a template to build the unique network structure, which is conductive to accommodate the volume expansion of MnO during the cycles. The synthesized MnO/C hybrid reveals a superior electrochemical performance when applied to lithium-ion batteries. A high reversible capacity of 978 mAh g(-1) can be retained at a current density of 0.2 A g(-1). This synthesis strategy based on biomass provides a possibility for large-scale preparation of high-capacity electrode materials.