Al2O3 exists in several polymorphs (γ, δ, θ, etc.), which progressively transform into the thermodynamically stable α-phase at elevated temperatures. In the present work, Al2O3 nanoparticles were synthesized via the SCS route and subsequently annealed at 500, 700, 900, and 1200°C to induce controlled phase transformations. XRD confirmed the sequential γ → δ→ α transitions with increasing annealing temperature. FTIR verified the evolution of Al-O vibrational modes, while SEM revealed distinct and smooth structures in the α-phase. EDX confirmed compositional purity, UV-Vis absorbance and reflectance analyses showed band gap widening and a reduction of defect states, while PL spectra demonstrated the disappearance of defect related emissions and the emergence of α-phase specific features. The correlation of structural, morphological and optical studies with XRD establishes a comprehensive understanding of the γ → δ→ α transformations in Al2O3, providing valuable insights into tailoring alumina phases for advanced functional applications.