In this study, a simple method to enhance the conductivity of poly(3,4-ethylenedioxythiphene):poly(styrenesulfonate) (PEDOT:PSS) thin films from 0.7 to 1185 S/cm by post-treatment with dimethyl sulfoxide (DMSO) is demonstrated. After the rubbing technique was applied, the DMSO-treated PEDOT:PSS film was used as both transparent electrode and alignment layer to fabricate ITO-free liquid crystal (LC) cells. The electro-optical properties of LC cells fabricated by rubbed PEDOT:PSS were compared to those constructed by ITO and polyimide. This work indicates that highly conductive PEDOT:PSS film is a promising material for ITO-free LC devices.