Strontium titanate nanoparticles (SrTiO3 NPs) were produced via the solid-state reaction method. Then, they were used to enhance the structural, mechanical, electrical, and dielectric properties of polyvinyl alcohol (PVA)/polyethylene oxide (PEO) blend for energy storage applications. For this purpose, SrTiO3 NPs were dispersed in the polymer blend to fabricate nanocomposite films using a solution casting method. The nanocomposite films were then characterized using a variety of instruments, such as transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-Transform Infrared spectroscopy (FTIR), Ultraviolet/Visible spectroscopy (UV/visible), and impedance analyzers. Based on XRD and TEM measurements, the synthesized SrTiO3 NPs have a cubic perovskite phase and a diameter that varies between 70 and 160 nm. Additionally, according to XRD measurements, adding SrTiO3 NPs to PVA/PEO reduces the crystallinity of the resulting nanocomposites. In addition, the surface morphology and elemental composition were demonstrated through the utilization of scanning electron microscope.(SEM) and energy dispersive X-ray spectroscopic analysis (EDX) spectra, where PVA and PEO polymers formed a homogenous and rough surface, and the SrTiO3 NPs of low concentrations were spread out within the blend's structure. Analysis of the FTIR peaks revealed prominent characteristic peaks associated with vibrational groups that change randomly with the concentration of SrTiO3 NPs. With increasing SrTiO3 NPs concentration, the nanocomposite UV/visible absorbance, optical bandgap energies, and refractive index were calculated and discussed. Impedance studies conclude that the amount of SrTiO3 NPs in a mixture raises the mixture's AC electrical conductivity, dielectric loss, and dielectric constant. The mechanical characteristics, such as Young's modulus, yield strength, and strain at failure, were assessed by examining the tensile test of prepared films. The thermal stability of PVA/PEO-SrTiO3 nanocomposite films were studied by thermogravimetric analysis (TGA). These experimental results point to the potential for employing the produced nanocomposites in optoelectronic and capacitive energy storage systems.