This research presents a novel p-BiOBr-p-Mn3O4 heterostructure nanophotocatalyst fabricated via a simple precipitation deposition route. Various characterization techniques, including XRD, FESEM, DRS, EDX, FTIR, TEM, BET-BJH, PL and PSD have been used to investigate the optical and physicochemical features of the samples. Degradation of acid orange 7 (AO7) was applied in order to investigate the photoactivity of as-synthesized nanophotocatalysts under simulated sunlight irradiation at room temperature. It was disclosed that deal of Mn3O4 is a deciding factor in the photocatalytic properties of BiOBr-Mn3O4. The optimum percentage of Mn3O4 in the samples was situated at 10 (wt.%) content, which exhibited superior photoactivity in comparison to other corresponding samples or pure samples with almost 97% AO7 degradation. The enhanced photo catalytic activity of BiOBr(90)-Mn3O4(10) is ascribed to the separation efficiency of the carriers. Additionally the effects of catalyst loading, pH, dye concentration were investigated for the nanophotocatalyst with optimum weight percentage.