The synthesis and characterization of thin films of polyaniline/carbon nanotubes nanocomposites is reported, as well as their utilization as transparent electrodes in ITO-free organic photovoltaic devices. These films are generated by interfacial synthesis, which provides them with the unique ability to be deposited onto any substrate as transparent films, thus enabling the production of flexible solar cells using substrates like PET. Very high carbon nanotube loadings can be achieved using these films without significantly affecting their transparency (≈80–90% transmittance at 550 nm). Sheet resistances as low as 300 Ω/□ are obtained using secondary polyaniline doping in the presence of carbon nanotubes. These films present excellent mechanical stability, exhibiting no lack in performance after 100 bend cycles. Flexible and completely ITO-free organic photovoltaic devices are built using these films as transparent electrodes, and high efficiencies (up to 2.27%) are achieved.