FePMo12O40@PVP composite materials were synthesized with the regulation of polyvinylpyrrolidone (PVP) to control the structure. The samples were characterized by FT-IR, XRD, XPS, SEM, TEM and UV-Vis DRS. The composite retains the Keggin-type polyoxometalates structure, exhibiting a high specific surface area that enhances photon capture efficiency. Analysis of UV-Vis DRS absorption band edge and band gap indicated that the composite was responsive to visible light. Photocatalytic degradation of Rhodamine B (RhB) by FePMo12O40@PVP was investigated under commonly used LED light source, demonstrating excellent photocatalytic performance as 2.5 g-FePMo12O40@PVP (0.015 g) can remove 83% of RhB (10 mg/L) in 40 min. The FePMo12O40@PVP composite material demonstrated sustained moderate degradation efficiency even after undergoing three cycles of repeated use. The non-covalent interaction and strong interfacial coupling between PVP and FePMo12O40 promoted the transfer of h+, and e−, ∙O2−, ·OH, and h+ served as the primary active species in this photocatalytic system. This environmentally friendly material has the potential to significantly reduce energy consumption and offers valuable insights for the future treatment of dye wastewater.