In this study, graphene oxide (GO) nanosheets were first functionalized by the acyl-chloride reaction and then reacted with hindered phenol (HP) to obtain HP grafted GO (GO-g-HP). The GO-g-HP prepared under the op-timized condition exhibited a high efficiency against both thermal and photo oxidation of isotactic poly-propylene (iPP). GO-g-HP exhibited a much better anti-aging efficiency than that of HP and GO used individually or that of their physical mixture. The outstanding anti-aging effect of GO-g-HP was attributed to the excellent synergistic effect produced between the chemically bonded GO and HP, which resulted in an improved oxygen barrier property of GO and excellent utilization of the free radical scavenging capability of GO and HP. Also, thanks to the grafting of HP on GO, the physical loss of HP, which was one of the main shortcomings for traditional small molecular antioxidants, was largely suppressed. It is expected that the GO-g-HP prepared can well meet the requirement of long-term applications of polymers in some harsh service conditions.