Conjugated small molecules bearing the cyano group were reviewed. These organic compounds are extensively used as active layers of solar cells and light-emitting diodes as well as materials with high second- and third-order nonlinearities. Typical organic light conversion agents are also based on CN-capped pi-conjugated scaffolds that, in addition, are also increasingly popular for building various organic sensors and probes. More recently, cyanoarenes and dicyanopyrazines were identified as efficient photoredox catalysts. Fundamental structure-property relationships of CN-capped molecules used across the aforementioned areas were elucidated and discussed. The cyano group possessing electron-withdrawing character and linear arrangement is capable of significantly altering electronic and optical properties, and supramolecular arrangement. Hence, extensive property tuning/regulation through the CN group has been demonstrated.