<p>Polymer nanocomposites have emerged as promising materials for advanced optical and electrical applications due to their ability to integrate the unique properties of both polymers and nanofillers. Here, we synthesised polysulfone/zinc selenide (PSU/ZnSe) nanocomposite thin films with varying weight percentages of zinc selenide (ZnSe) nanofiller through the solution casting method and analysed various characteristic features in the optical and electrical domains. Subsequent morphological investigations provided valuable insights into the surface topography and dispersion of ZnSe in the polymer nanocomposites. Different polarisation effects occur in the PSU matrix and ZnSe nanofiller in response to external electrical fields, as explained by the Maxwell-Wagner-Sillars (MWS) theory. The direct optical band gap was reduced from 3.4 to 3.22&#xa0;eV in the PSU/ZnSe (2 wt%), calculated from UV–visible absorption data combined with the Tauc plot method, which is consistent with the dielectric studies of the system. Notable photoluminescence quenching was marked in the presence of ZnSe nanoparticles. The quenching efficiency is ~ 80% with 1 wt% ZnSe load, decreases to ~ 60% at 2 wt%, and then appears to saturate at higher concentrations. So, 2 wt% is the optimal concentration exhibiting desirable optical and electrical properties for the PSU/ZnSe nanocomposite films. This investigation provides valuable insights into the tunable optical and electrical properties enabled by controlled nanofiller incorporation, paving the way for their applications in next-generation flexible devices.</p> Graphical abstract <p></p>