Finding an effective strategy to promote the charge transfer and separation of TiO2 is urgently needed. Herein, a surface fluorination (F-)-modified TiO2 (denoted as TO-xF, where x represents the volume of HF added in the solution) catalyst has been prepared by a mild and facile post-treatment method. The changes induced by surface F- on the morphological, structural, and surface electronic features and the charge separation and transfer efficiency of TiO2 were specifically examined. Compared with pristine TO, TO-0.4F exhibits enhanced photocatalytic degradation of methyl orange and phenol, production of hydroxyl radicals, and photocurrent response. The enhanced photocatalytic activities of TO-0.4F can be attributed to the role of surface F- as surface trapping sites in effectively boosting the charge transfer and separation processes, which is verified by the steady-state and time-resolved fluorescence spectroscopy, electrochemical impedance spectroscopy, Bode plot, transient photocurrent response, and open-circuit voltage measurements. This study emphasizes the role of surface F- in promoting the charge transfer and separation and improving the photocatalytic activity of TiO2.