The nanotubes and nanofibers of polyaniline (PANI) were successfully synthesized by a template-free and interfacial polymerization method respectively in the presence of tetrakis(4-sulfonatophenyl)porphyrin (TSPP) as a dopant. The tubular and fibrous morphologies of the TSPP–PANI were confirmed by TEM images. The morphology of TSPP–PANI can be changed from nanotube to cauliflower by simply changing the volume ratio of the dopant to the aniline monomer as confirmed by SEM images. It was observed that the formation of nanotubes (by the template-free method) was independent of the dopant, but the dopant was associated with interfacial polymerization for the formation of nanofibers. It might be the electrostatic and hydrophobic interactions between the water dispersible porphyrin complex [TSPP–(NH₄)₂S₂O₈] and the dimer cation-radical surfactant which are responsible for the formation of nanofibers. The resulting materials were also characterized by conductivity, solubility, FTIR and UV-vis spectroscopy, X-ray diffraction and cyclic voltammetry.