1,2,4-Thiadiazoles, a significant class of heterocyclic compounds, are widely found in biologically active molecules. Herein, we report a green electrochemical three-component reaction of amines, amidines, and CS2 for the effective synthesis of 3,5-disubstituted-1,2,4-thiadiazoles under metal- and oxidant-free conditions. Both aliphatic and aryl amines are well-tolerated at room temperature in a simple undivided cell. A series of 1,2,4-thiadiazoles are prepared with excellent functional groups.