<p>This paper investigates the synthetic, structural, optical, and electrical characteristics of composites, including polyvinyl alcohol (PVA), iron oxide (Fe₂O₃), and silicon dioxide (SiO₂) nanoparticles (NPs). Rapid production of flexible nanocomposite (NC) samples was achieved using the cast synthesis process, including PVA, Fe₂O₃, and SiO₂ nanoparticles. Furthermore, the structures of the produced samples were analyzed using optical microscopy and Fourier transform infrared (FT-IR) spectroscopy. The optical characteristics of the PVA NCs were enhanced with an increase in the Fe₂O₃/SiO₂NPs, as evidenced by ultraviolet–visible (UV/Vis) spectroscopy. The band gaps of PVA-Fe₂O₃/SiO₂ polymer nanocomposites decreased from 4.46 eV to 2.24 eV for allowed transitions and from 3.79 eV to 0.53 eV for prohibited transitions as the nanofiller concentration increased; this indicates a shift towards semiconductive behavior. The Urbach tail energy (<i>E</i>_u), linear susceptibility (<i>χ</i>⁽¹⁾), nonlinear susceptibility (<i>χ</i>⁽³⁾), nonlinear refractive index (<i>n</i>₂), average oscillator parameter (<i>λ</i>₀), zero-frequency dielectric constant (<i>ε</i>₀₎, and zero-frequency refractive index (<i>n</i>₀) increases with the increase of nanoparticles, while single-oscillator energy (<i>E</i>_oso), dispersion energy (<i>E</i>_d), and average oscillator strength(<i>S</i>₀) decreased. Incorporating more significant percentages of (Fe₂O₃/SiO₂) led to an increase in the range of refractive index (<i>n</i>) (1.40–2.89), extinction coefficient (<i>K</i>) (6.05 × 10^–5–9.96 × 10^–4), real dielectric constant (<i>ε</i>₁) (1.96–8.4), and optical conductivity (6.17 × 10¹⁰–2.14 × 10¹² S⁻¹) at a wavelength of 400 nm in these NC films. The electrical properties of alternating current (AC) of nanostructures, notably the dielectric constant and dielectric loss, exhibited a decrease as the frequency increased. Conversely, a greater concentration of Fe₂O₃/SiO₂ nanoparticles resulted in an enhancement of these properties. The best AC conductivity was obtained at 6 wt.% of Fe₂O₃/SiO₂ nanoparticles in the PVA polymer, and this was 4.39 × 10⁻¹² S/cm at 100 Hz. The findings demonstrate that the PVA-Fe₂O₃/SiO₂ nanostructure films possess exceptional electrical and optical capabilities, making them very attractive for utilization in various quantum electronics and optical nanodevices. The study’s results regarding the utilization of gamma shielding demonstrate that the nanocomposites composed of PVA-Fe₂O₃/SiO₂ display significant attenuation coefficients for gamma rays.</p>