Ce and N elements were selected as dopants for modifying the surface of carbon dots to obtain a novel Ce@N-CDs inhibitor. The structure and inhibition ability of the as-obtained Ce@N-CDs were analyzed by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and electrochemical workstation. The results showed that the Ce@N-CDs inhibitor exhibited good dispersion in solution with average particle size of about 3 ∼ 6 nm. Electrochemical measurements indicated that the corrosion resistance of metal (Q235 steel) in aggressive solution (1 M HCl) was greatly enhanced after adding Ce@N-CDs inhibitor. The inhibition efficiency was up to 96.4% when the addition amount of Ce@N-CDs was 200 mg/L. This inhibition effect was mainly due to the physicochemical adsorption and the formation of Ce-containing ligand complexes on corrosion interface, which was confirmed by the XPS analysis of corrosion product.