Transition metal oxide (TMO)—filled polymer films have numerous applications, including electromagnetic shielding and nonlinear optical devices. Nb2O5-filled polyvinyl pyrrolidone (PVP)/polyvinyl alcohol (PVA) blend was prepared using a solution casting process. Pristine and nanocomposite films from these blends were studied. X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier infrared spectroscopy confirmed the formation of nanocomposites via interfacial interactions between the polymer chains and Nb2O5 nanoparticles. These nanoparticles influence the amorphous nature and transparency of the PVA/PVP blends. The improvement of Dopt (optical density) becomes particularly obvious in blended polymer films with considerable Nb2O5-nanofiller concentrations. By increasing the weight percentage of Nb2O5, the probability of producing additional levels in the bandgap increased. The optical absorption coefficient of each nanocomposite film was less than 106 m
1 , indicating indirect electron transfer. Thus, the indirect optical band-gap declined from 3.9 to 1.9 eV as calculated from Tauc's and the absorption spectral fitting (ASF) formula. Additionally, the effects of Nb2O5 on the extinction coefficient, refractive index, highfrequency (ε∞), and static-frequency (εo) dielectrics have been reported. The nonlinear refractive index and optical susceptibilities (x1 and x3 ) were enhanced by increasing the Nb2O5 content in the blend. The penetration depth (δ) and optical limiting (OL) properties were also investigated. The developed nanocomposite materials could be used for advanced technologybased devices such as reflective coatings, opto-linear, and nonlinear optoelectronic applications