An abnormal level of SO₂ is closely related to many diseases. Therefore, developing an effective method for the detection of SO₂ in biological environments has important physiological and pathological significance. In this work, a new fluorescent probe (CA-SO₂) was designed and synthesized for efficiently and specifically detecting SO₂ derivatives through nucleophilic addition reaction. The novel fluorescent probe (CA-SO₂) showed high selectivity, fast response time (within 50 s), and low detection limit (LOD = 75 nM). Furthermore, after adding SO₂ derivatives to the probe solution, the color of the solution changes from orange to colorless, which allows “naked eye” detection for SO₂. Moreover, the probe has a large Stokes shift (129 nm) and excellent biocompatibility. The probe has been successfully applied to the detection of SO₂ derivatives in living cells and zebrafish.