The current study proposed outstanding thin films of NaIO3 doped PVA with higher linear and nonlinear optical parameters using a practical, effective, simple, and low-cost approach. Polymeric thin films based on the combination of the polyvinyl alcohol (PVA), used as a matrix, with sodium iodate (NaIO3) nanoparticles, considered a filler, were synthesized using a solution casting approach. The structural morphology of pure PVA and NaIO3 doped PVA nanostructured films was investigated though X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) images. The obtained XRD results concluded an increase in the crystallinity of the host PVA polymer matrix as the weight concentrations of the NaIO3 dopants increase. SEM images illustrated the external structure morphology of the prepared films, where the cluster agglomeration shows a size increased as increasing the weight concentration of NaIO3 in the PVA matrix. UV-VisNIR spectroscopy was used in this study to study the optical enhancement of the NaIO3/PVA nanocomposites as a function of the weight concentration of sodium iodate (NaIO3) nanoparticles. In this proposed study, it was critical to consider some of the NaIO3/PVA optical parameters, including transmittance, absorbance, absorption and extinction coefficients, energy bandgaps, refractive index, optical and electrical conductivities, nonlinear parameters, linear and third nonlinear susceptibilities, and nonlinear refraction coefficient, as well as optical limiting effects. It was observed that with the increase in the NaIO3 weigh concentrations, the values of the direct and indirect energy bandgaps for NaIO3/PVA thin films decrease, compared to the host PVA matrix. The proposed NaIO3 doped PVA nanocomposites are outstanding promising candidates to pave the way in various optoelectronic devices, taking advantage of the amazing linear optical parameters, huge nonlinear optical properties, low optical energy bandgaps, and large optical limiting.