Polymer networks such as those of epoxy resin, as common protection materials, possess radiolytic oxidation degradation effects under gamma irradiation environment, which have a great accelerating effect on the ageing rate and severely limit their potential applications for metal protection in the nuclear industry. To overcome this, we report a simple scheme of anchoring crystalline ceria nanoparticles onto graphene sheets (CG) and incorporate it into the epoxy resin, followed by thermal polymerization to obtain CeO2/graphene-epoxy nanocomposite coating (CGNS). We had proven that graphene might act as "interwalls" in the epoxy matrix, which will result in space location-obstruct effect as well as absorb the radicals induced by γ-ray irradiation. Moreover, owing to the interconversion of cerium ions between their +3 and +4 states coupled with the formation of oxygen vacancy defects, electron spin resonance (ESR) detection shows that CeO2/graphene (CG) could act as a preferable radical scavenger and achieve better performance in trapping radicals than single graphene based composite. Electrochemical data strongly demonstrate that CeO2/graphene is capable of maintaining the anti-corrosion properties under gamma irradiation environment. Therefore, the designed hybrid CeO2/graphene-epoxy composite can be considered as potential candidates for protective coatings in nuclear industry.