Well-crystalline CeO 2 –ZnO composite nanoellipsoids (NEs) were synthesized by facile hydrothermal process at low-temperature and characterized in detail in terms of their morphological, structural, optical and compositional properties. The detailed characterizations revealed that the synthesized CeO 2 –ZnO NEs are pure, grown in high density, possessing well-crystallinity and exhibiting good optical properties. Finally, the prepared NEs were used as efficient electron mediators for the fabrication of 4-nitrophenol chemical sensors. The fabricated sensor exhibited a reliable and reproducible sensitivity of ∼0.120μA/nMcm 2 and detection limit of 1.163μM. To the best of our knowledge this is the first report in which CeO 2 –ZnO NEs were used as efficient electron mediators for the fabrication of 4-nitrophenol chemical sensors. The presented work demonstrates that simply prepared nanocomposites can effectively be used for the fabrication of efficient, reliable and robust chemical sensors.