In this work, a polyethyleneimine-grafted graphene oxide (PEI-GO) hybrid material was prepared as an effective filler to improve the anticorrosion performance of waterborne epoxy coating. The successful covalent reaction between PEI and GO was confirmed by FTIR, Raman, XPS, XRD and TGA measurement. The epoxy coating filled with modified and unmodified graphene oxide was characterized by SEM and Raman spectroscopy. The results showed that PEI-GO was uniformly dispersed in the epoxy matrix. It was found that the PEI-GO hybrid materials displayed considerable superiorities in improving corrosion resistance of epoxy coating by EIS and SVET. Besides, the optimal content (0.25 wt%) of PEI-GO was obtained through experimental results. Moreover, the desirable anticorrosive property of PEI-GO/EP composite coating is proposed to be mainly attributed to the role of PEI, which fully stimulated the barrier properties of graphene oxide by improving its dispersion in the epoxy coating and also enhanced the crosslink density of epoxy resin by increasing the surface activity of the graphene oxide to the epoxy groups. Display omitted •Polyethylenimine (PEI) was grafted on graphene oxide (GO) surface.•The PEI-GO hybrid improved the compatibility between GO and epoxy resin (EP).•The PEI-GO/EP composite coating had longer service life and better anti-corrosion property.•The presence of PEI-GO hybrid increased the density of epoxy coating and suppressed the corrosion of metal substrate.