A ternary composite of polypyrrole (PPy), Prussian blue (PB), and graphene oxide (GO), PPy⿿PB⿿GO, was successfully prepared through spontaneous polymerization of pyrrole and formation of PB nanocubes on GO. The obtained nanocomposite was characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. The results indicate that the PPy-protected PB nanocubes were well dispersed on the GO. Electrochemical testing showed a specific capacitance of 525.4Fg⿿1 at a current density of 5Ag⿿1 in the potential range from ⿿0.2 to 0.6V, obtained in an electrolyte of 1molL⿿1 KNO3 during the galvanostatic charge⿿discharge cycles, which is superior to the performance of binary cathode materials, including PPy⿿PB and PPy⿿GO nanocomposites. The as-prepared supercapacitor could retain a specific capacitance of 96% after 2000 cycles. It was confirmed that the three components⿿PPy, PB, and GO⿿led to the display of integrated electrochemical behavior and a resulting capacitor with enhanced performance. The significant enhancement in electrochemical performance of the ternary nanocomposite can be attributed to the synergistic effect of PPy-protected PB nanocubes dispersed on GO sheets with the pseudocapacitance from PB and PPy on the double-layer capacitance from GO.