A new BODIPY-based near-infrared (NIR) fluorescent probe, based on the deprotection of dithioacetal, has been developed, with good selectivity for Hg2+. The proposed sensing mechanism was supported by (HNMR)-H-1 studies. Moreover, the probe was successfully applied to the fluorescence imaging of Hg2+ in Human Hepatoma SMMC-7721 cells under physiological conditions.