This article demonstrates the successful synthesis of indium selenide thin films by a spin coating method in air using thiol-amine cosolvents. The synthesized films encountered a transformation from β-In₃Se₂ to γ-In₂Se₃ phase due to mechanical stress during annealing as confirmed from XRD and EDS analysis. The SEM study ensured the homogeneity and uniformity of surface morphology of both phases. The FTIR analysis also confirmed the In–Se stretching vibration bond for both β-In₃Se₂ and γ-In₂Se₃ thin films. The temperature dependent electrical conductivity indicated the semiconducting nature of both phases. The optical transmittance was found to increase with annealing temperatures for both phases. The optical band gaps were estimated to be in the range of 2.60–2.75 and 2.12–2.28 eV for β-In₃Se₂ and γ-In₂Se₃ phases, respectively consistent with the reported values. These results indicate that stress-induced phase transformation in solution-processed indium selenide could be useful in 2D optoelectronic devices in future.