A simple naphthoquinone–dopamine hybrid (2CND) was designed and fabricated as a colorimetric and fluorescence chemosensor for the selective recognition of Sn2+ in the aqueous medium. This simply accessible chemosensor was prepared by connecting of naphthoquinone acceptor and dopamine donor moieties via Michael-like addition reaction. The chemosensor 2CND showed a turn-on fluorescence response which operated through the inhibited photoinduced electron transfer effect. The sensor probe shows remarkable performance, such as high selectivity, sensitivity, excellent water solubility, and rapid response to Sn2+ (less than 5 s). The detection mechanism of the 2CND–Sn2+ complex was supported by FT-IR analysis, 1H NMR titration, and DFT calculations. Besides, the 1:1 binding stoichiometry was confirmed by the ESI-MS spectral analysis. Furthermore, the chemosensor 2CND has been successfully employed as a fluorescence probe to monitor trace Sn2+ in live cells and zebrafish. The sensor probe 2CND could serve as an effective fluorescence bioimaging probe for the discriminative detection of diseased and normal human cells.