Poly(aniline-co-m-aminophenol)(PANMA)/graphene/NiO nanocomposite was synthesized and applied as a supercapacitor electrode for the first time. Graphene/NiO nanocomposite was first synthesized via a hydrothermal synthesis method from Ni(NO3)2·6H2O, urea, and graphite oxide. NiO nanoparticles were distributed uniformly on both sides of the graphene. Then, PANMA was deposited in situ on the surface of the graphene/NiO nanocomposite viathe copolymerization of aniline and m-aminophenol. The obtained nanocomposite has a similar porous morphology with that of PANMA. Experimental results indicate that the synergistic contributions from PANMA, graphene and NiO enable the composite electrode with substantially improved energy storage performance metrics. The nanocomposite shows a high specific capacitance of 562Fg−1 at a current density of 0.5Ag−1, a good rate capability even at high current densities and a better long-term cycling stability.