The study successfully prepared PVA/SrTiO₃/CNT polymer nanocomposite films using the solution casting method. The structural, optical, and thermal properties of these films were characterized using XRD, SEM, FTIR, TGA, and UV-visible spectroscopy. The inclusion of SrTiO₃/CNT nanofillers at up to 1 wt% significantly improved the optical and thermal properties of PVA films. SrTiO₃ has a cubic crystal structure with an average crystal size of 28.75 nm. SEM images showed uniform distribution of 0.3 wt% SrTiO₃/CNTs in the PVA film, while agglomerations appeared at higher concentrations (0.7 and 1.0 wt%). The thermal stability of the films was enhanced, with the onset of the second degradation stage increasing from 235 °C for pure PVA to 310 °C for doped PVA. The direct and indirect optical band gaps of PVA films decreased with increasing mass percentage of SrTiO₃/CNTs, while the single-oscillator energy (E₀) and dispersion energy (Eₐ) increased. The refractive indices of the films gradually increased with the increasing mass of nanofillers. Additionally, improvements in optical susceptibility and nonlinear refractive indices were observed. These films exhibit promising optical and thermal properties suitable for optoelectronic applications.The study successfully prepared PVA/SrTiO₃/CNT polymer nanocomposite films using the solution casting method. The structural, optical, and thermal properties of these films were characterized using XRD, SEM, FTIR, TGA, and UV-visible spectroscopy. The inclusion of SrTiO₃/CNT nanofillers at up to 1 wt% significantly improved the optical and thermal properties of PVA films. SrTiO₃ has a cubic crystal structure with an average crystal size of 28.75 nm. SEM images showed uniform distribution of 0.3 wt% SrTiO₃/CNTs in the PVA film, while agglomerations appeared at higher concentrations (0.7 and 1.0 wt%). The thermal stability of the films was enhanced, with the onset of the second degradation stage increasing from 235 °C for pure PVA to 310 °C for doped PVA. The direct and indirect optical band gaps of PVA films decreased with increasing mass percentage of SrTiO₃/CNTs, while the single-oscillator energy (E₀) and dispersion energy (Eₐ) increased. The refractive indices of the films gradually increased with the increasing mass of nanofillers. Additionally, improvements in optical susceptibility and nonlinear refractive indices were observed. These films exhibit promising optical and thermal properties suitable for optoelectronic applications.