A novel chemosensor based on the Zn²⁺–isonicotinohydrazide complex ‘(ZnL)’ was developed for the selective detection of cyanide (CN⁻) over other tested anions, such as HSO₄⁻, F⁻, Cl⁻, Br⁻, I⁻, NO₃⁻, PO₄³⁻, SO₄²⁻, SCN⁻, S²⁻, CH₃COO⁻ and H₂PO₄⁻ in 80% MeOH (organic–aqueous medium). The detection of CN⁻ with (ZnL) could be possible with both UV-visible and fluorescence responses without any interference effects from other anions. This system shows excellent sensitivity with a lower detection limit of 5.49 nM.