<p>Polymer nanocomposites have been developed using polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) as base polymers, with iron (III) oxide (Fe₂O₃) and molybdenum trioxide (MoO₃) serving as nanofiller materials. The results of XRD and FTIR studies verified the effective integration of FeO₂/MoO₂ nanoparticles into the polymer matrix and their interactions with polymer chains, which resulted in changes to the crystalline structure and chemical bonding of the nanocomposite. The SEM analysis reveals that adding mineral oxides (Fe₂O₃/MoO₃) to the PVA/CMC blend transitions the morphology from smooth and homogeneous to increasingly disordered due to filler-induced aggregation. As the Fe₂O₃/MoO₃ concentration increased, the indirect optical bandgap reduced from 4.43 to 2.88&#xa0;eV, improving the photoresponsiveness of the material. Moreover, the refractive index rose from 1.63 to 2.72, indicating the material’s suitability for optical applications. The magnetic properties of the PVA/CMC-Fe₂O₃/MoO₃ nanocomposite were evaluated at room temperature using the VSM technique, showing ferromagnetic behavior with a notable rise in saturation magnetization (Ms), remanent magnetization (Mr), and loop area (La) as the Fe₂O₃/MoO₃ content increased. The prepared films demonstrated higher AC conductivity values than the pure PVA/CMC. The dielectric permittivity and modulus display tunable properties, offering promising potential with different concentrations of PVA/CMC-Fe₂O₃/MoO₃ nanoparticles in the PVA/CMC matrix. These results underscore the promise of PVA/CMC-Fe₂O₃/MoO₃ nanocomposites for optoelectronic applications, where key factors for example enhanced light absorption, an increased refractive index, and improved charge transport play a crucial role in device performance.</p> Graphical Abstract <p>The preparation steps of PVA/CMC-Fe₂O₃/MoO₃ nanocomposite films.</p> <p></p>