The efficient utilization of near-infrared (NIR) light is an important challenge to extend the spectral response range of photocatalysts. Here, the NIR photocatalytic performance of Bi3O4Br nanosheets was significantly enhanced by a rare earth ion doping strategy that synergistically utilizes the dual mechanism of photon conversion and energy band modulation. Under 980 nm excitation, the Bi3O4Br:Er3 + nanosheets exhibit near-single-band green upconversion (UC) emission and are reabsorbed by Bi3O4Br. Combined with DFT density of states calculations, it is shown that the band gap of the material has been lowered and the carrier transport paths have been optimized by the energy-band structural tuning. In the NIR photocatalytic degradation experiment of bisphenol A, Bi3O4Br was not degraded, and Bi3O4Br:Er3+ showed better performance, which was 2.27 times higher than that of Bi3O4Br:Yb3+, Er3+. ESR testing and capture experiments indicate that under NIR light irradiation, center dot OH and e- are the primary active species in the photocatalytic reaction process. This work provides new design ideas for the development of efficient NIR photocatalytic materials.