In this study, three types of amine-functionalized graphene oxide (f-GO) have been synthesized and their polyurethane (PU) composites have been fabricated. Mechanical properties and the anticorrosion performance of as-prepared composites were thoroughly investigated. The amine groups (two aliphatic groups and one aromatic group) on GO influenced the dispersion of the fillers and the properties of the composites. Among the f-GO series, GO functionalized with 2-naphthyl amine (2NA-GO) indicated higher mechanical properties and corrosion resistance than other PU composites. Specifically, the incorporation of 0.5 wt % of 2NA-GO in the PU matrix showed a 2.2 times higher tensile modulus than the neat PU and the highest protection efficiency of 99.94%. This synergetic effect of 2NA-GO was due to the aromatic structure and relatively low molecular weight of 2NA. The aromatic structure developed pi-pi interfacial interactions between the amine group and phenyl groups of the hard segments in the PU backbone. Furthermore, the lower molecular weight contributed to the uniform dispersion of the filler. Based on the results, molecular structure and molecular weight could be a critical factor in designing the f-GO to improve the mechanical and corrosion properties of PU composites. Additionally, this fact can be contributed to PU industries, which require a high anticorrosion performance as well as enhanced mechanical properties.