PbBiO2Br/ZnO heterojunction composites are synthesized using a one‐step method. The as‐synthesized samples are characterized by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), field‐emission scanning electron microscopy (FE‐SEM), energy‐disperse X‐ray spectroscopy (EDX), transmission electron microscopy (TEM), Fourier‐transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET), ultraviolet‐visible diffuse reflectance spectroscopy (UV‐vis DRS), and photoluminescence (PL) spectroscopy. The photocatalytic activity of the PbBiO2Br/ZnO heterojunction composites is assessed by measuring the removal of methyl orange (MO) from wastewater under simulated sunlight irradiation. The results demonstrate that the PbBiO2Br/ZnO heterojunction composites are composed of ZnO nanorods and PbBiO2Br cubic nanosheets. The PbBiO2Br/ZnO heterojunction composites exhibit enhanced photocatalytic performances for the degradation of MO under irradiation by simulated sunlight. Among the composites, the 10% PbBiO2Br/ZnO composite exhibits optimal activity, and the removal percentage of the dye reaches 92.1% after 60 min of reaction. This is mainly attributed to the efficient separation of photo‐generated e−–h+ pairs and the formation of heterojunctions. According to the active species trapping experiments, photo‐generated h+ is confirmed to be the main active species, whereas ·boldObold2bold− and ·OH play a secondary role in the reaction process. Additionally, the recycling experiments suggest that the PbBiO2Br/ZnO composites have good stability in the reaction process.