Oriented arrays of polyaniline (PANI) nanorods grown on expanded graphite (EG) nanosheets are fabricated by in situ polymerization to achieve excellent electrochemical properties for applications as supercapacitor electrodes. EG serves as an excellent 3D conductive skeleton that supports a highly electrolytic accessible surface area of redox-active PANI and provides a direct path for electrons. The porous and ordered nanostructure provides a larger contact surface area for the intercalation/deintercalation of protons into/out of active materials and shortens the path length for electrolyte ion transport. The maximum specific capacitance of 1665 F g–1 at 1 A g–1 is observed in the PANI/EG electrode with 10% EG content. The composite electrode material also exhibits significant rate capability and good long-term cycling stability. The results demonstrate that PANI is effectively utilized with the assistance of EG conductive skeletons in the electrode. Such 3D composite nanoarchitecture is very promising for the next generation of high-performance electrochemical supercapacitors.