A novel samarium doped ferrite composite material was prepared successfully by using the chemical co-precipitation method, which was used for the photocatalytic degradation of perfluorooctanoic acid (PFOA). The samarium doped ferrite was characterized by XRD, FT-IR, SEM, XPS, UV–vis and VSM. The results revealed the catalyst could be a typical soft magnetic material with a spinel structure, which has uniform particle size (100–200 nm), and good photoresponse in the wavelength range of 200–700 nm. Satisfactory photocatalytic activity of the samarium doped ferrite material was verified, that is the PFOA (0.5 mmol L⁻¹) with degradation efficiency of 48.61% could be achieved in 120 min under UV irradiation at 185 nm. After conducting the cycle experiments, excellent stability and good magnetic recovery performance of the samarium doped ferrite were found. The free radical capture test signified that the h⁺ and •OH could play major roles in the PFOA initial oxidation, simultaneously. Moreover, possible mechanisms of the PFOA degradation was studied by analyzing the intermediate products using the HPLC method. These results suggest that samarium doped ferrite is a promising photocatalyst in the PFOA wastewater treatment.