A pure Ti target in Ar/O₂ gas mixture was used to synthesize Ti₃O_x thin film on a glass substrate by Reactive High-Power Impulse Magnetron Sputtering (HiPIMS) under different sputtering power (2 and 2.5 kW). The influence of HiPIMS parameters on thin films’ structural, morphological, chemical composition, optical and photocatalytic, and antibacterial properties was investigated. In this study, Ti₃O_x thin films can be synthesized using the HiPIMS method without the post-annealing process. Two co-existence phases (hexagonal Ti₃O and base-centered monoclinic Ti₃O₅ phases) existed on the Ti₃O_x films. It is found that the peak intensity of (006) Ti₃O hexagonal slightly increased as the sputtering power increased from 2 to 2.5 kW. The Ti₃O_x thin-film bandgap values were 3.36 and 3.50 eV for 2 and 2.5 kW, respectively. The Ti₃O_x films deposited at 2.5 kW showed good photocatalytic activity under UV light irradiation, with a higher methylene blue dye degradation rate than TiO₂ thin films. The antibacterial study on Ti₃O_x thin films exhibited a high inhibition percentage against E. coli and S. aureus. This study demonstrates that Ti₃O_x thin films can promote high photocatalytic and antibacterial activity.