Copper (II) is one of the most of important cofactors for numerous enzymes and has captured broad attention due to its role as a neurotransmitters for physiological and pathological functions. In this article, we present a reaction-based fluorescent sensor for Cu2+ detection (NIR-Cu) with near-infrared excitation and emission, including probe design, structure characterization, optical property test and biological imaging application. NIR-Cu is equipped with a functional group, 2-picolinic ester, which hydrolyzes in the presence of Cu2+ with high selectivity over completed cations. With the experimental conditions optimized, NIR-Cu (5μM) exhibits linear response for Cu2+ range from 0.1 to 5μM, with a detection limit of 29nM. NIR-Cu also shows excellent water solubility and are highly responsive, both desirable properties for Cu2+ detection in water samples. In addition, due to its near-infrared excitation and emission properties, NIR-Cu demonstrates outstanding fluorescent imaging in living cells and tissues. •A reaction-based sensor for Cu2+ detection with NIR excitation and emission.•The detection limit for Cu2+ is as low as 29nM in aqueous buffer.•The probe shows special selectivity for Cu2+ over other metal ions.