A julolidine-nitroaniline conjugate as a new simple colorimetric chemosensor 1 for the detection of both F − and CN − has been developed. This sensor could simultaneously detect two biologically important anions (F − and CN − ) through colorimetric methods over most other competitive anions. It exhibited a distinct color change from yellow to orange upon addition of F − through deprotonation process. In addition, the sensor 1 displayed an obvious color change from yellow to colorless upon binding with CN − through a nucleophilic addition mechanism. Thus, this sensor exhibits a new method to simultaneously assay F − and CN − with different color change in the same solvent environment.