The enzymatically catalyzed polymerization of 3,4-ethylenedioxythiophene in the presence of polystyrenesulfonate is introduced. This is the first time that an enzymatically catalyzed poly(3,4-ethylenedioxythiophene) (PEDOT) is reported. Horseradish peroxidase enzyme was used as a catalyst for the polymerization process leading to a water-soluble PEDOT that was characterized by UV-vis spectra, Fourier transform infrared, and electrical conductivity measurements. Water-soluble PEDOT showed excellent film formation ability as confirmed by atomic force microscopy images.