Flower-like Bi2O2CO3 and g-C3N4-Bi2O2CO3 microspheres with a high adsorption ability were synthesized using a facile method, and their dye-induced photosensitized degradation activity under visible light irradiation was evaluated. The as-synthesized samples were characterized by XRD, FT-IR, FESEM, TEM (HRTEM), UV-vis DRS and nitrogen adsorption-desorption techniques. It was found that the activity of Bi2O2CO3 was significantly enhanced due to the generation of g-C3N4-Bi2O2CO3 heterostructures. The dye-sensitization and the presence of g-C3N4 are beneficial for the visible-light excited process. The enhancement of photocatalytic performance is ascribed to the proper matching of the energy levels of the dye, Bi2O2CO3 and g-C3N4 that facilitates the separation and transfer of photogenerated electrons and holes at the heterojunctions. The results of the present study give insights that are beneficial for the design of heterostructured materials.