Polyaniline/graphene nanocomposites with microspherical morphology and porous structure are prepared as electrode materials for supercapacitors. Using few-layer graphene obtained by liquid phase exfoliation of graphite as the raw material, porous graphene microspheres are produced by spray drying, and are then employed as the substrates for the growth of polyaniline nanowire arrays by in situ polymerization. In the composite, interconnected graphene sheets with few structural defects constitute a high-efficient conductive network to improve the electrical conductivity of polyaniline. Furthermore, the microspherical architecture prevents restacking of polyaniline/graphene composite nanosheets, thus facilitates fast diffusion of electrolytes. Consequently, the nanocomposite exhibits excellent electrochemical performance. A specific capacitance of 338 F g−1 is reached in 1 M H2SO4 at a scan rate of 20 mV s−1, and a high capacity retention rate of 87.4% after 10,000 cycles at a current density of 3 A g−1 can be achieved, which suggests that the polyaniline/graphene composite with such kind of 3D architecture is a promising electrode material for high-performance supercapacitors.