A facile solvothermal approach assisted with a [C16mim]Br ionic liquid for the preparation of BiOBr visible-light photocatalytic films was developed. A BiOBr film with uniformly assembled nanosheets was stably grown on the pretreated soda glass substrate via the Bi-O-Si bond. A rotating disk reactor coated with the BiOBr film was designed to effectively avoid the light shielding from color solution. The BiOBr film obtained with the [C16mim]Br ionic liquid presented an improved visible-light photcatalytic degradation rate of organics in wastewater, especially at a high concentration of organic dyes with deep color. A stable combination of BiOBr films with the substrate, the enhanced light harvesting owing to multiple reflections within the network of BiOBr nanosheets, the high separation efficiency of photo-induced charge carriers, the fast adsorption rate and the efficient utilization of light in the rotating disk reactor simultaneously played important roles in the degradation process, leading to the applicable future for the practical wastewater treatment.