Abstract: A Na4Fe3(PO4)2P2O7/C composite (denoted as NFPP-E) featuring a highly graphitized N, P co-doped carbon coating and hierarchical pore structure has been successfully synthesized via a facile ball milling–calcination approach. Herein, ethylenediamine tetra (methylene phosphonic acid) (EDTMPA) acts as a multifunctional precursor, concurrently serving as the chelating agent, phosphorus source, carbon source, nitrogen source, and pore-forming agent. The unique “phosphorus-catalyzed graphitization” effect during EDTMPA pyrolysis plays a pivotal role: the released active phosphorus oxides remarkably facilitate the ordered transformation of the carbon matrix, thereby yielding a highly graphitized N, P co-doped carbon coating with low defect density. Electrochemical measurements demonstrate significant performance enhancements of NFPP-E relative to the sample prepared with conventional NH₄H₂PO₄. Specifically, NFPP-E delivers a high reversible capacity of 103.09 mA h g-1 at 0.1 C and retains 77.41 mA h g-1 even at an elevated rate of 10 C, manifesting excellent rate capability. Furthermore, it exhibits superior long-term cycling stability, with a capacity retention rate of 94.5% after 500 cycles at 1 C. When assembled into a full cell with hard carbon as the anode, NFPP-E achieves a capacity retention rate of 93.3% over 200 cycles, highlighting its great potential for practical applications. This work not only uncovers the universal principle for regulating the structure and properties of the carbon layer via the “phosphorus-catalyzed graphitization” mechanism using organic phosphonic acid precursors but also offers a novel strategy for the development of high-performance and low-cost cathode materials for sodium-ion batteries