Directed by an unusual in situ reduction of Cu^II, our protocol is a simple Cu^I‐mediated synthesis of aryl nitriles, with inexpensive and readily available nitromethane as the cyanating source, in moderate to good yields. Exhibiting a wide substrate scope, the method involves simple reaction conditions, is additive free with low catalyst loading. The plausible mechanism of cyanation of aryl halides is elucidated by a congregation of three cycles, namely the in situ reduction of Cu^II species by nitromethane, generation of HCN species from nitromethane and a regular organometallic pathway which releases the nitrile derivative. The detail of the mechanism of generation of CN^– from nitromethane is computationally validated. Our protocol holds the distinction of involving a rarely encountered Cu^I catalytic species as well as facile in situ generation of nucleophilic CN^– to yield synthetically useful aromatic nitriles.