<p>This study explores the effects of thermal annealing on the structural and optical properties of Sb₂Se₃ thin films, which has shown promising results in various optoelectronic applications. The thin films were prepared using the thermal evaporation technique and subsequently annealed at 250 °C and 350 °C to investigate the effects of post-annealing on their crystallinity, morphology, and band gap tuning. X-ray diffraction technique (XRD) revealed that annealing induced a transition from amorphous to polycrystalline phases with enhanced crystallinity as the annealing temperature increased. Raman spectroscopy confirmed the desired phase, the increase in peak intensity following annealing indicates enhanced structural order. Field Emission Scanning Electron Microscopy (FESEM) investigation showed sharper grain boundaries at 250&#xa0;°C, while 350&#xa0;°C annealed films exhibited overgrowth and irregular morphology. Despite minor compositional changes, Energy Dispersive Spectroscopy (EDS) verified that the Sb₂Se₃ films retained near-ideal stoichiometry throughout the annealing process. Ultraviolet–visible (UV–VIS) spectroscopy revealed the pseudo-direct band gap nature of Sb₂Se₃. These results demonstrate that moderate annealing improves the structural and optical quality of Sb₂Se₃ thin films; however, excessive annealing can negatively impact the film morphology.</p>