An efficient and controllable approach to prepare cross-linked films from a conjugated polymer precursor by electrochemical deposition (ED) is reported for the first time. A novel polymer precursor with high solubility, high electroactivity, and electron-transport ability has been designed. The electrochemically deposited polymer film shows high thickness, smooth morphology, and high fluorescence. The single-layer pure-blue-emitting ED PLED exhibits a luminous efficiency of 3.8 cd A(-1).