In this article, the polyaniline nanorods/graphene sheet composites (G-PANI) with covalent bond were synthesized through interfacial copolymerization of aniline and functionalized graphene (G-PPD) obtained by in situ reduction of graphene oxide and functionalization with para-phenylenediamine (PPD). During the interfacial polymerization, the monopolymerization of aniline and copolymerization of aniline and G-PPD are carried out simultaneously, which produce a mixture of PANI nanorods and G-PANI. Not only the homopolymer possesses one-dimensional structure, but also the graphene surface was covered evenly by the PANI nanorods. As comparison with conventional synthesis methods of PANI, the interfacial polymerization can produce large-scale one-dimensional PANI nanorods, which can form a loose crisscross aggregation. Even when it is grafted onto graphene sheet, the nanorod morphology is remained. The cyclic voltammetry (CV) and charge-discharge tests confirm that the G-PANI has higher electrochemical activity and higher capacitive properties over those of neat PANI nanorods. At the current density of 1 mAcm−2, the specific capacitance of G-PANI and PANI nanorods are 909 Fg−1 and 772 Fg−1, respectively. Especially, the specific capacitance of G-PANI has 62% enhancement over that of PANI nanorods at high current density of 50 mAcm−2. The remarkable improved capacity performance can be attributed to the enhanced mass transfer process brought from the loose nanostructure aggregation of G-PANI, as well as the reduced charge transfer resistance caused by the highly conductive graphene and strong interfacial interaction between PANI and graphene via covalent bond.