Herein, using the auto-combustion method, a BiFeO₃/Bi₂O₃ composite was successfully synthesized for the photocatalytic degradation of nitrobenzene under visible illumination. The compound was subsequently characterized using varied characterization approaches, including XRD, SEM/EDS, FTIR, XPS, and UV–VIS techniques. The photocatalytic capability of the resulting sample was assessed by removing nitrobenzene (NB) under solar and artificial (15 W LED lamp) exposure. Within 180 and 240 min of exposure, the prepared BiFeO₃/Bi₂O₃ composite exhibited impressive photocatalytic ability with quasi-total elimination (100%) of NB under both solar and LED lights, in contrast to pure oxides. The photocatalytic capability of BiFeO₃/Bi₂O₃ was 2.88 and 1.67 folds higher than those of BiFeO₃ and Bi₂O₃. This was linked to the effective charge splitting occurring at the BiFeO₃/Bi₂O₃ interface and the lower recombination ratio of charge carriers. Additionally, BiFeO₃/Bi₂O₃ exhibited outstanding sustainability without loss of activity during the first 5 cycles. Aside from this, quenching investigation showed that ^•OH was responsible for the degradation process. Furthermore, total organic carbon (TOC) analysis confirmed NB mineralization. Based on these previous findings, an appropriate mechanism for NB decomposition was established. Overall, the BiFeO₃/Bi₂O₃ photocatalyst is recommended for use in the efficient photocatalytic removal of organic contaminants owing to its straightforward manufacturing approach, high levels of degradation, and strong structure for potential uses.