The protective performance of graphene/polymer composite coatings largely depends on the interface design in resin matrix. Herein, we report the synthesis of bio-based cardanol epoxy modified graphene oxide (GODN) nanomaterial and its application in epoxy coatings for the achievement of fine interface toward high performance anticorrosion composite coatings. The chemical composition of prepared GODN nanomaterial was investigated by FTIR, Raman and XPS spectra, respectively. The presence of cardanol epoxy attached on GO surface promotes the formation of chemical bonds between GO and epoxy resin, providing strong interfacial interaction and enhanced adhesion. Electrochemical results revealed that the GODN1%/EP composite coating exhibits high impedance (4.38 x 10(8) Omega cm(2)) even after 45 days immersion. Compared with pure EP coating, the localized corrosion reaction of GODN1%/EP coating can be inhibited under defected interface. The enhanced protective performance of GODN/EP composite coating was attributed to two aspects: (1) the impermeable GO greatly suppressed the penetration of aggressive ions and (2) the attached cardanol epoxy chains effectively improved the interfacial interaction and thus inhibited the crack propagation. (c) 2020 Elsevier Inc. All rights reserved.