A general and efficient hydrothermal strategy combined with a high-temperature carbon-coating technique has been developed for large scale synthesis of self-assembled LiFePO4/C nano/microspheres employing the biomass of phytic acid as a novel and eco-friendly phosphorus source. The LiFePO4/C nano/microspheres are investigated by SEM, TEM, EDS, XRD, Raman spectroscopy, and electrochemical techniques. A reasonable assembly process of the hierarchical structure is proposed on the basis of time-dependent experimental results. Because of the unique structure, the LiFePO4/C nano/microspheres show a high tap density of 1.2 g cm–3, a high reversible specific capacity of 155 mA h g–1 at 0.1 C, as well as excellent rate capability and cycling performance, exhibiting great potential as superior cathode materials in lithium ion batteries. The approach for the preparation of LiFePO4 by using PA as the phosphorus source may open new prospects for utilization of biomass to produce high performance cathode materials for lithium ion batteries.