A simple innovative anthraimidazolyldione (LHSi) based colorimetric and ratiometric fluorescent chemodosimeter was designed and synthesized for fluoride and cyanide ion sensing. Upon reaction with the F⁻ and CN⁻ anions in THF solution, probe LHSi shows dramatic color changes from light yellow to red and remarkable ratiometric fluorescence enhancement signals. These properties are mechanistically ascribed to a fluoride/cyanide-triggered deprotonation and C–Si bond cleavage that resulted in a green to red fluorescence.