Asteroidal/cometary impacts should have delivered a large amount of organic matter to Earth and other planets during the heavy bombardment period. Most of the delivered organics, however, would decompose through either severe shock heating upon impact or intense aerodynamic interaction with the ambient atmosphere. Here, we demonstrate that organics decomposed by intense aerodynamic interactions following oblique impacts will be converted to CN radicals under a wide range of redox conditions within primitive atmospheres. High-speed spectroscopic observations reveal that the nitrogen and the carbon comprising CN are derived from both the atmosphere and impact-fragmented projectile materials, respectively. The yield of CN relative to C₂ (a direct vaporization product of projectile materials) increases with both impact velocity and the ratio of N₂ partial pressure to the total atmospheric pressure. Such impact-driven cyanide synthesis may have significantly contributed to basic compounds (particularly nitrogen-rich ones) necessary for the origin of life.