This study details the successful incorporation of zinc tin oxide nanoparticle (ZTO-NPs) into polyvinyl alcohol (PVA) using the hydrothermal method. We introduce a streamlined and integrated synthesis approach, representing a novel direction for polymeric composite films with wide-ranging applications. This was achieved by creating a nanocomposite in a PVA matrix using ZTO-NPs composite as a filler at different concentrations that can be extended to use in many applications, such as optoelectronics. The study delves into the impact of ZTO-NPs loadings on the optical, electrical, and structural properties of PVA films across different concentrations. Structural analysis of ZTO-NPs and resulting ZTO/PVA nanocomposite films is performed using X-ray diffraction (XRD), while Fourier transform infrared (FT-IR) analysis confirms the interaction between ZTO-NPs and PVA. Atomic force microscopy (AFM) is employed to analyze surface morphology and roughness, while diffuse reflectance spectroscopy (DRS) reveals enhanced UV absorption and a red-shift with increased ZTO-NPs concentration. Moreover, the optical band-gap decreases with higher ZTO-NPs concentration. Electrical properties, including dielectric constant, dielectric loss, conductivity, and electric modulus, are investigated at room temperature across different frequencies, indicating an increase in dielectric constant with ZTO-NPs concentration.