Fluorescence of the anthracene fragment of the supramolecular system 1 is reversibly switched on/off through the Cu-I/Cu-II redox couple inside the appended tetrathia ring. The OFF state is generated through a thermodynamically favored electron transfer process from anthracene excited state *An to Cu-II, which quenches fluorescence. The Cu-I-to-*An electron transfer process is not thermodynamically favored, and fluorescence is revived (ON state). On/off switching of anthracene fluorescence can be carried out at will, by consecutively varying the potential of the working electrode in a controlled-potential electrolysis experiment.