In this work, single-crystal gallium oxide (β-Ga2O3) thin films were epitaxially grown on different off-cut angled c-plane sapphire substrates by metal organic chemical vapor deposition (MOCVD), and the effect of off-cut angles on the crystal quality and surface roughness of the epitaxial films were investigated. For the β-Ga2O3 epilayer grown on the 6° off-cut angled sapphire substrate, the full width at half maximum (FWHM) of the rocking curve is reduced to be 1.10°, together with the smallest surface roughness of 7.7 nm. Consequently, the metal-semiconductor-metal structured solar-blind ultraviolet photodetectors were fabricated by lithography, development, electron beam evaporation and lift-off techniques. The photodetector has excellent performances, including photo-dark current ratio of 6.2×106, peak photoresponsivity of 87.12 A/W at 248 nm, specific detectivity of 3.5×1015 Jones, UV-visible rejection ratio of 2.36×104, and total response time of 226.2 μs.