Corrosion of steel reinforcement in concrete is one of the major issues in reducing the service life and durability performance of reinforced concrete (RC) structures. Carbon fiber-reinforced polymer (CFRP) as a triple-functional material in the impressed current cathodic protection (ICCP) system has been innovatively investigated in this study. An experimental program comprising three kinds of current densities of 0 mA/m2, 20 mA/m2 and 100 mA/m2 is presented in RC beams. All specimens are under a simulated harsh environment of 3.5% NaCl solution at 50 °C, wet-dry cycle, and sustained loading. The constant current density of 20 mA/m2 was found to be sufficient for the ICCP system, a higher current density is not needed even without using the conductive epoxy. The experimental results confirmed that CFRP can not only be used as a strengthening material, but also play a coating layer and ICCP anode role for sustainable protection of RC structures against corrosion.