In this Communication, we report on the development of a ratiometric fluorescent probe for silver(I) ions (Ag-I) based on an arene-metal ion interaction. The probe selectively senses Ag-I among various metal ions with a large-emission red shift under aqueous conditions, enabling the selective ratiometric detection of Ag-I. X-ray crystallography and NMR analyses reveal that Ag-I comes into close contact with the fluorophore, which induces a large-emission red shift. The high sensing selectivity of the probe toward Ag-I might be attributable to the restricted rigid conformation of the cyclic aza crown ether, which exclusively binds Ag-I. In addition to Ag-I sensing, the Ag-I complex of the probe is also used for the ratiometric sensing of a cyanide anion (CN-), highlighting the utility of the reported probe in fluorescence sensing.