Copper is an essential trace element for the proper functioning of organ and metabolic process in humans. However, both its excess and deficiency in the body can result in adverse health effects. A BODIPY containing 2,2'-bipyridyl group was synthesized and used as a fluorescent chemodosimeter for selective Cu2+ detection in mild condition. This BODIPY shows fast response (~1 min) and high sensitivity for Cu2+ in aqueous solution due to the photoinduced electron transfer from the excited state of fluorophore to the bipyridyl unit complexed to Cu2+. The fluorescence quenching mechanism revealed by MALDI-TOF Mass spectra showed one Cu2+ could coordinate with two BODIPY molecules, and this coordination is reversible. This simple BODIPY dyes also could be used for sensing the Cu2+ in living cell. This work contributes to extend the potential applications of BODIPY to the biological and environmental areas.