N-doped carbon quantum dots/Zn0.4Co0.6Fe2O4(N-CQDs/ZnCF) composite was successfully synthesized by a hydrothermal method.XRD, HR-TEM, UV–Vis/DRS,PL, andXPSwere used to characterize the synthesized nanoparticles. The band gap energies of the synthesized nanomaterials were found to be less than 2 eV. PL results confirmed improved separation efficiency of photo-generated carriers on the N-CQDs/ZnCF. Additionally, HR-TEM images showed quasi-spherical and cubic morphology for both N-CQDs and ZnCF, respectively. The XPS survey spectra of 10% N-CQDs/ZnCF confirmed the presence of Zn2+, Co2+, Fe3+, N, O, and C on surfaces of N-CQDs/ZnCF. The pristine NPsand N-CQDs/ZnCF NCswere tested for the photodegradation of oxytetracycline, under visible light irradiation. The 10% N-CQDs/ZnCF nanocomposite showed the highest photocatalytic activity of up to 98% in 100 min. This enhancement was attributed to the synergistic effect of N-CQDs and ZnCF in the heterojunction, which promotes charge carrier separation and boosts photoactivity in degrading OTC.