AbstractThe synthesis and application of the bio‐derived flame retardant can meet the current requirements for the high‐efficient and sustainable development of flame retardants. Therefore, using phytic acid (PA), 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO), and piperazine as raw materials, a PA‐derived flame retardant (PAPDOPO) was prepared. Fourier transform infrared spectroscopy and x‐ray diffraction techniques were applied to characterize the structure of the PAPDOPO. In the prepared flame‐retardant epoxy resin (FEP), PAPDOPO showed high flame retardancy. When 4% PAPDOPO was added into epoxy resin (EP), the prepared FEP (EP‐PAPD‐4) passed the V‐0 level in the UL‐94 test, and the limited oxygen index value of EP‐PAPD‐4 reached 35.3%. Microcombustion calorimetry test was also applied to demonstrate the performance of PAPDOPO. The peak heat release rate of EP‐PAPD‐4 was reduced by 30.4% compared with that of the pure EP. Due to the low addition amount of PAPDOPO in FEP, the mechanical properties of the FEP using PAPDOPO as flame retardant were hardly decreased compared with pure EP.