Electron-transfer behaviors of conjugated polymers on electrode (electrochemical doping) have been studied well for the purpose of electrochemical device applications such as conducting material and electrochromic material. In this study, we treated a charged (doped) state of conjugated polymers as an intermediate for following chemical reactions based on the concept of electroorganic synthesis. The post-functionalization of conjugated polymers was successfully achieved when a reactive dopant (conter ion derived from electrolyte) was used for the electrochemical reactions. For example, the polymer reactions such as anodic halogenations, cathodic reduction, and gradient oxidation reaction on bipolar electrode were successfully carried out to tune the optical and electrochemical properties of the polymers.