Recent results concerning the derivatization of electrode surfaces with crown ether-functionalized films are reviewed. The most commonly used approach consisted in the incorporation in π-conjugated polymers from the chemical or electrochemical oxidation of the substituted monomers. The optical and electrochemical responses of such systems could be modified in the presence of some guest cations owing to the complexation by the host macrocycle. Other properties such as the electron conductivity could be also changed. Moreover, the incorporation of crown ethers in self-assembled mono- and multilayers has been proposed as an alternative route to modify electrode surfaces.