β-Ga₂O₃ is an ultra-wide bandgap semiconductor promising for high-power electronic applications; however, heteroepitaxial growth on sapphire is challenging lattice and symmetry mismatch. In this study, β-Ga₂O₃ thin films were grown on C-plane sapphire substrates with various off-axis angles (0–12°) using mist-CVD, and the influence of substrate miscut on structural and optical properties was investigated. All films grown at 900°C exhibited (-201) oriented β phase. The crystal quality was strongly dependent on the off-axis angle, with intermediate off-axis angles (Δ_a = 6–8°) showing the narrowest rocking curve width. Off-axis substrates promoted step-aligned growth behavior compared to on-axis growth. Optical measurements revealed enhanced transmittance and wider bandgap values (4.92–4.95 eV) for off-axis samples compared to the on-axis film (4.69 eV). The findings provide practical guidelines for optimizing heteroepitaxial β-Ga₂O₃ growth on low-cost sapphire substrates for high-performance device applications.