A highly selective and sensitive fluorescent sensor for mercury ion has been obtained from a combination of Bodipy and Calix[4]arene derived by click chemistry. The structural characterization of all compounds had been carried out by FT-IR, 1H NMR, 13C NMR, MS, elemental analysis or melting point. Calix[4]-B including a calix[4]arene and two Bodipy units is a good fluorescent sensor for Hg(II). It can be explained by the coordination between mercury and the triazole rings. In a co-solvent of methanol and water, the complexation ratio for Calix[4]-B/Hg(II) was determined as 1:1 and the binding constant was found to be 3.42 × 10 7 M−1. The detection of Hg(II) by Calix[4]-B works selectively in aqueous methanol mixture.