Cyanide ions (CN⁻) are widely used in chemical and industrial processes, but not only can they cause environmental pollution, what is worse is that when a small amount of cyanide enters the human body, in the less severe cases, they pose health risks, and in the more severe cases, they can lead to death. The development of a practical cyanide probe is extremely urgent. In this work, with α,β-unsaturated ketones conjugated with ethylenediamine coumarin as a fluorophore and reaction site, boron fluoride was introduced to adjust the ICT and reactivity to construct a ratiometric fluorescent probe for the highly sensitive detection of CN⁻. The process was rapid within 40 s and can be monitored by the naked eye. The probe demonstrated a low detection limit (0.072 μM). Furthermore, the probe was used to detect CN⁻ in the test strip, soil, and water. In addition, cell imaging experiments indicated the probe can be used in biological determination of cyanide poisoning.