The BiOBr/Ag3PO4 composites were fabricated by a facile in situ deposition of Ag3PO4 nanoparticles on the BiOBr microsheets and analyzed by X-ray diffraction, scanning electron microscope, high resolution transmission electron microscope, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance absorption spectra, Fourier transform infrared, Raman, photoluminescence (PL), and photoelectrochemical techniques. The photocatalytic performances of as-prepared samples were investigated and compared through degradation of Rhodamine B (RhB) solution. The results suggested that 30 wt% amount of BiOBr in the composites possessed the highest photocatalytic activity. The remarkably improved photocatalytic performances of BiOBr/Ag3PO4 composites could be ascribed to the efficient separation of electron–hole pairs, due to suitable energy band potentials between BiOBr and Ag3PO4. Furthermore, the photoelectrochemical and PL tests verified the separation and transfer efficiency of charges was promoted.