Increasing the efficiency of dye degradation is a critical issue for the application for photocatalysis. It is one of the greatest challenges to enhance the utilization of photo generated carriers in semiconductor, especially for sunlight irradiation. In this study, I/C-codoped TiO2 was synthesized by a simple solvothermal-calcination method. The codoping interstitial carbon and substitutional iodine not only widened the light absorption range of the TiO2 photocatalysts, but also enhanced the separation of photo-induced carriers. The photocatalytic activities of RhB and MO degradation over the 4-I/C-TiO2 photocatalyst could reach 98.2% and 94.2% after 25 min visible light irradiation (lambda >= 400 nm), respectively. Notably, 4-I/C-TiO2 showed good activity for MO and RhB mixed degradation and could also accomplish the photocatalytic degradation in the above mixed system under natural sunlight irradiation. According to the dark catalytic experiment, I/C-codoping could effectively accelerate the formation of hydroxyl radicals from the generated H2O2, which was formed for the enhanced photo catalytic activity of dye degradation. The gained knowledge may provide some insights into the photocatalytic degradation over the codoped TiO2 catalyst.