A new cyanide anion colorimetric probe was developed using a chromene derivative, 7-nitro-2,3-dihydro-1H-cyclopenta[b]chromen-1-one (1). The molecule exhibited much higher selectivity and sensitivity for detecting cyanide anion compared with other anions, F-, Cl-, Br-, 1(-), SCN-, AcO-, NO3-, ClO4-, SO42-, PO43-, SO32-, CO32-, and C2O42-, in aqueous media through a visual color change from colorless to yellow. The mechanism was proposed to be a novel chromene ring-opening, resulting from a nucleophilic attack on the probe 1 by CN- anion.