Ag-BiOBr-reduced graphene oxide (rGO) was synthesized for the first time and used to promote photocatalytic activity under visible-light irradiation. The Ag-BiOBr-rGO showed an excellent photocatalytic activity to degrade ketoprofen compared with other photocatalysts. The composites were comprehensively characterized to explore the mechanisms of the enhancement. Electron Paramagnetic Resonance and scavenger experiments demonstrated that the superoxide radical was the active species. Ketoprofen was completely removed in 120 min. The high photocatalytic activity and stability of the catalyst indicated that the Ag-BiOBr-rGO may have broad application prospects for eliminating pharmaceuticals from wastewater. Four reaction intermediates of ketoprofen were detected by LC-MS/MS and degradation routes were proposed.