The carbon film with electroless nickel interlayer (Ni+C) was fabricated to improve the corrosion resistance of the magnesium alloy GW83. Compared to other coatings used in this study, the dense Ni+C coating improved adhesion with the substrate. The corrosion potential (Ecorr) of the Ni+C coated magnesium alloy was about −1.37V vs saturated calomel electrode (SCE) in contrast to about −1.67V vs SCE of the bare one in 3.5wt% NaCl solution. The corrosion current density was reduced from 186μAcm−2 to 11μAcm−2. The 5h immersion test revealed that the Ni+C coated magnesium alloy GW83 showed much less corrosion compared to the bare alloy. These evidences indicated that applying Ni+C coating could effectively improve the corrosion resistance of the magnesium alloy GW83.