Biodegradable polymers with flame retardancy have aroused great interest in the fabrication of biobased flame retardants. In this study, nickel phytate (PA‐Ni) was prepared by reaction of phytic acid from plant seeds with nickel acetate in water and then used as flame retardant added into polylactic acid (PLA) with intumescent flame retardant (IFR). With the loading of 4 wt% PA‐Ni and 11 wt% IFR, the resulted PLA composite can achieve a UL94 V‐0 test rating. The results show that the pHRR of PLA/11IFR/4PA‐Ni decreases by 62.3% compared with that of virgin PLA and residual char increases significantly. The flame retardant mechanism was analyzed by scanning electron microscopy–energy‐dispersive x‐ray spectroscopy and thermogravimetric analysis coupled to Fourier transform infrared spectroscopy. It is showed that PA‐Ni can improve the formation of continuous and compact char residues, and phosphorus‐containing compounds can act as a radical scavenger to quench free radicals generated during combustion, suggesting that gas‐phase flame retarded mechanism coexists with condensing phase flame retarded mechanism.