This study investigates the structural, optical, and thermal properties of PVA/SrTiO₃/CNT polymer nanocomposites prepared via solution casting. The inclusion of SrTiO₃/CNT nanofillers up to 1 wt% significantly improved the optical and thermal properties of PVA films. SrTiO₃ has a cubic crystal structure with an average size of 28.75 nm. SEM images showed uniform distribution of 0.3 wt% SrTiO₃/CNTs in PVA films, while higher concentrations led to agglomeration. The thermal stability of PVA films was enhanced, with the onset of the second degradation stage increasing from 235 °C to 310 °C. The optical band gaps of PVA films decreased with increasing SrTiO₃/CNT content, while single-oscillator energy (E₀) and dispersion energy (E_d) increased. The refractive index of the films increased with higher nanofiller content, and improvements in optical susceptibility and nonlinear refractive indices were observed. These films exhibit promising optical and thermal properties suitable for optoelectronic applications. The study highlights the potential of PVA/SrTiO₃/CNT nanocomposites for use in optoelectronic devices due to their enhanced optical and thermal characteristics.This study investigates the structural, optical, and thermal properties of PVA/SrTiO₃/CNT polymer nanocomposites prepared via solution casting. The inclusion of SrTiO₃/CNT nanofillers up to 1 wt% significantly improved the optical and thermal properties of PVA films. SrTiO₃ has a cubic crystal structure with an average size of 28.75 nm. SEM images showed uniform distribution of 0.3 wt% SrTiO₃/CNTs in PVA films, while higher concentrations led to agglomeration. The thermal stability of PVA films was enhanced, with the onset of the second degradation stage increasing from 235 °C to 310 °C. The optical band gaps of PVA films decreased with increasing SrTiO₃/CNT content, while single-oscillator energy (E₀) and dispersion energy (E_d) increased. The refractive index of the films increased with higher nanofiller content, and improvements in optical susceptibility and nonlinear refractive indices were observed. These films exhibit promising optical and thermal properties suitable for optoelectronic applications. The study highlights the potential of PVA/SrTiO₃/CNT nanocomposites for use in optoelectronic devices due to their enhanced optical and thermal characteristics.