Hierarchical plush polypyrrole (PPy) layers intercalated graphene sheets have been prepared by in-situ intercalative chemical polymerization. The as-prepared graphene/PPy nanocomposites have been successfully characterized in terms of composition, morphology, and electrochemical properties. It was found that the chemically modified graphene nanosheets and in-situ polymerized PPy layers formed uniform nanocomposites with homogeneous PPy layers intercalated between the graphene substrates. Such uniform nanostructure together with the observed high conductivities (the highest 1980Sm−1) afforded the graphene/PPy composites with high specific capacitance and good cycling stability during the charge–discharge process when used as supercapacitor electrodes. The graphene/PPy (with optimized composition 10:1) based supercapacitors display intriguing performance with a maximum specific capacitance of 650Fg−1 at 0.45Ag−1 current density, a highest energy density of 54.0Whkg−1 at 1mA current, and a highest power density of 778.1Wkg−1 at 5mA current. Furthermore, the graphene/PPy supercapacitor exhibits an excellent cycling stability with 95% specific capacitance retained after 5000 cycles. The impressive results presented here may open the window for grapheme/PPy composites for their promising applications in high energy density storage system.