Nanostructured β-Ga 2 O 3 with a needle-like structure was synthesized by a polyvinyl alcohol (PVA)-assisted hydrothermal method and subsequent heat treatment. It has a high specific surface area (25.95 m 2 /g) and large number of nanopores (4–25 nm), and it exhibited good photocatalytic activity for perfluorooctanoic acid (PFOA) decomposition in pure water unde UV irradiation (λ = 254 nm). PFOA had a half-life of 18.2 min, and the first order rate constant (2.28 h −1 ) for PFOA decomposition with the needle-like β-Ga 2 O 3 was 7.5 and 16.8 times higher, respectively, than with commercial Ga 2 O 3 and TiO 2 (P25). In addition, in combination with vacuum UV (VUV) irradiation (λ = 185 nm), the needle-like β-Ga 2 O 3 showed high activity for the removal of trace PFOA in both pure water and wastewater, with first order rate constants of 4.03 and 3.51 h −1 , respectively. The adverse effect that coexisting natural organic matters in wastewater have on the decomposition of PFOA was mostly eliminated with VUV irradiation, and the energy consumption in this method was much less than the values reported for other methods in the literature.