Aligned carbon nanotube–oriented poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) composites show an unexpectedly high catalytic activity which greatly exceeds the aligned individual components, the non-aligned composite counterpart, and even conventional platinum. When they are used as counter electrodes in dye-sensitized solar cells, the aligned composites also exhibit a highest energy conversion efficiency of 8.3%. The synergetic interaction between the nanotubes and polymers by aligned organization is the key to this new phenomenon.