This paper reports significant enhancement of corrosion resistance and electrical properties of waterborne epoxy coatings through additions of ceria modified graphene. Results showed that ceria particles were uniformly distributed and covalently bonded onto the surface of graphene. A dense interface layer was formed between the ceria modified graphene and epoxy matrix by aliphatic ether bonds. The composite coating with a modified graphene content of 0.5 wt% exhibited the best corrosion resistance with the highest impedance modulus (e.g., 103 Ω cm2 for the damaged coating) and the lowest corrosion rate (e.g., 0.002 mm/year). The excellent corrosion resistance of the composite coating is related to the barrier effect of graphene and the inhibition effect of ceria on metal corrosion. Moreover, the coating showed a low percolation threshold of 0.231 vol% and its electrical conductivity reached 10−5 S/m when the content of modified graphene was 0.5 wt%.