Cerium oxide nanoparticles (CeO₂ NPs) are favorable in nanotechnology based on some remarkable properties. In this study, the crystalline CeO₂ NPs are successfully prepared by an efficient microwave combustion (MCM) and conventional route sol-gel (CRSGM) methods. The structural morphology of the as-prepared CeO₂ NPs was investigated by various spectroscopic and analytical techniques. Moreover, the XRD pattern confirmed the formation of CeO₂ NPs as a face centered cubic structure. The magnetometer studies indicated the low saturation magnetization (23.96 emu/g) of CeO₂ NPs for weak paramagnetic and high saturation magnetization (32.13 emu/g) of CeO₂ NPs for super paramagnetic. After that, the oxidation effect of benzyl alcohol was investigated which reveals good conversion and selectivity. Besides, the CeO₂ NPs modified glassy carbon electrode (GCE) used for the detection of nitrite with linear concentration range (0.02–1200 μM), low limit of detection (0.21 μM) and higher sensitivity (1.7238 μAμM⁻¹ cm⁻²). However, the CeO₂ NPs modified electrode has the fast response, high sensitivity and good selectivity. In addition, the fabricated electrode is applied for the determination of nitrite in various water samples. Eventually, the CeO₂ NPs can be regarded as an effective way to enhance the catalytic activity towards the benzyl alcohol and nitrite.