<p>The present work reports a comparative study of chitosan-CeO₂ (CS-CeO₂) nanocomposite with different concentrations (0, 5, 15% w/v) of CeO₂ additives. The synthesize, surface morphology and optical properties of the prepared samples were comprehensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), thermal gravimetric analysis (TGA), and ultraviolet–visible spectroscopy (UV–vis) respectively. The results confirm successful incorporation of CeO₂ nanoparticles into the chitosan matrix with a cubic fluorite structure and uniform nanoparticle distribution. Increasing CeO₂ nanoparticle content induced clear morphological modifications and improved thermal stability of the composites. UV–vis analysis revealed enhanced light absorption and a significant reduction in optical bandgap values, indicating improved optical resistance. The refractive index, dielectric constant, susceptibility, and electronic polarizability all demonstrated a strong correlation with increasing content of CeO₂ nanoparticles. The metallization criterion decreased with higher CeO₂ content and found in the range of 0.394–0.375. These findings suggest that CS-CeO₂ nanocomposite are promising candidates in optoelectronic devices and nonlinear applications.</p>