Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been extensively used in various fields including organic light emitting diodes, actuators, sensors, and solar cells. Patterning of this conducting polymer is of practical importance, and many efforts have been devoted to fabricating PEDOT:PSS patterns on solid substrates. However, the majority of strategies developed for PEDOT:PSS patterning suffer from either poor conductivity or complicated protocols. Herein, we report a very efficient method for the fabrication of highly conductive PEDOT:PSS patterns. We were able to fabricate a highly conductive PEDOT:PSS film (∼2000 S/cm) on a flexible substrate by using the photo-crosslinkable and water soluble diacetylene diol hexa-2,4-diyne-1,6-diol (DADOL-1). Application of photolithographic technology to a thin film of PEDOT:PSS-DADOL composite allowed the generation of micron-sized PEDOT:PSS patterns. The simple photomasked UV irradiation/washing with water strategy developed in this study should be an important addition for meeting the increasing demand for highly conducting polymer patterns.