The widespread presence of pharmaceutical residues and dye contaminants in wastewater necessitates the development of efficient, low-cost photocatalysts. Here, zinc oxide/cerium oxide (ZnO/CeO2) composite nanoparticles were synthesized via a simple hydrothermal method, and their CeO2 content was optimized for the simultaneous degradation of ciprofloxacin (CIP), tetracycline (TC), methylene blue (MB), and methyl orange (MO). X-ray diffraction shows that ZnO retains its hexagonal wurtzite structure, while secondary CeO2 reflections appear at ≥ 5 mol% CeO2, indicating a ZnO/CeO2 composite. The composites exhibit pronounced morphology changes relative to pristine ZnO and a moderate increase in specific surface area at optimal CeO2 loading. Optical analysis reveals only slight band gap variations (3.13–3.16 eV) with increasing CeO2 content, whereas photoluminescence increases progressively, with ZnO/CeO2-5 showing the lowest PL among Ce-containing samples, suggesting a favourable balance between charge separation and recombination. Consequently, the 5 mol% ZnO/CeO2 composite displays superior photocatalytic performance in single-pollutant tests, binary mixtures (CIP + TC, MB + MO), and a four-pollutant mixture, demonstrating efficient removal of complex antibiotic–dye systems. The enhanced activity is attributed to the combined effects of Ce3+/Ce4+ redox chemistry, oxygen-vacancy-related surface states, and intimate ZnO/CeO2 interfacial contact. © 2026 The Author(s). Advanced Materials Interfaces published by Wiley-VCH GmbH.