The abundance of organic pollutants in the aqueous system has posed a serious threat to human health. Here, Co0.5Cu0.5Fe2O4 magnetic nanoparticles (NPs) were successfully synthesized for antibiotic degradation. The properties of the as-prepared photocatalyst were tested by diverse characterization techniques. The effects of the concentration of photocatalyst (20–100 mg L−1) and peroxymonosulfate (PMS) (20–80 mg L−1), and the pH (3–9) of solution on the degradation of tetracycline (TC) in aqueous solution by Co0.5Cu0.5Fe2O4/PMS/light system were investigated comprehensively. The results showed that Co0.5Cu0.5Fe2O4 NPs possessed remarkable photocatalytic performance over a wide pH range with the help of PMS and visible light irradiation. The degradation rate of TC could reach 86.0% at 40 min in the optimized conditions (TC = 10 mg L−1, catalyst = 60 mg L−1, PMS = 60 mg L−1, pH = 7). In addition, the active species quenching experiment demonstrated that h+, SO•4–, and •OH were generated in the degradation progress. Interestingly, h+ served as a conqueror in the reaction system, which benefited from the increased separation capability of electron-hole pairs due to the role of PMS as an electron quencher. Meanwhile, an improved PMS-assisted photocatalytic degradation of the TC reaction mechanism has been presented. Various TC intermediates were also uncovered, and probable degradation pathways were proposed. Furthermore, the Co0.5Cu0.5Fe2O4/PMS/light system was able to degrade a variety of organic pollutants, including naproxen sodium, naproxen, carbamazepine, ofloxacin, and flurbiprofen. The excellent degradation of various organics and high recyclability underline potential applications of Co0.5Cu0.5Fe2O4 NPs.