A new magnetic quaternary photocatalyst, K4Nb6O17/α-Fe2O3/Fe3N/g-C3N4, was synthesized via a simple one- step thermal pyrolysis process. The prepared photocatalyst was well characterized, and its photocatalytic ac-tivity was evaluated towards acetamiprid pesticide degradation, CO2 reduction reaction, and U87-MG cell eradication. The coexistence of four different crystalline structures in the prepared photocatalyst could simul-taneously facilitate photoelectron transport and suppress charge recombination through their coupled hetero-geneous interfaces. Because of the coexistence of various photosensitive compounds, the prepared photocatalyst showed the excellent capability to harvest the visible light photons despite its calculated high-bandgap of 2.75 eV. Besides, the magnetic saturation of about 12 emu/g facilitated the photocatalyst reusability. Benefiting from these favorable properties, the quaternary photocatalyst exhibited 76% removal efficiency for the degradation of acetamiprid pesticide after five times repeated cycles. The evolution rate of 7.01 and 1.3 μmol g
