The concurrent preservation of structural integrity and improvement of electrical conductivity in FeP2 anodes presents a persistent challenge. Herein, FeP2 nanoparticles embedded within a 3D N-doped honeycomb-like carbon framework composite (FeP2@NHC) are synthesized through a phosphorization process with a honeycomb-like Fe3C@NHC as a precursor. The in situ incorporation of FeP2 nanoparticles into the 3D carbon matrix effectively restrains the aggregation, pulverization, and stripping of material during cycling, and significantly enhances reaction kinetics and structural stability, achieving a superior electrochemical performance. Specifically, FeP2@NHC electrodes demonstrate remarkable reversible capacity (1433.9 mA h g−1 at 0.1 A g−1), excellent rate-capability (399.9 mA h g−1 at 10 A g−1), and ultra-long cycle life (631.5 mA h g−1 after 1000 cycles at 2 A g−1). Moreover, XRD analysis reveals that iron-rich Fe3C and Fe3O4 precursors can react with NaH2PO2 to form FeP2 and FeP, respectively. This study offers a rational and practical strategy for designing other phosphorus-rich metal phosphide anode materials.