A water-soluble fluorescent sensor, 1, based on the “receptor-spacer-fluorophore” [2-(2′-aminophenyl)benzoxazole-amide-2-picolylamine] sensor platform, demonstrates the high sensitivity for Zn²⁺ with a 25-fold fluorescence enhancement upon chelation to Zn²⁺ and also exhibits high selectivity to Zn²⁺ over other metal ions. X-ray crystal structure of Zn²⁺ complex reveals that the amide oxygen (O2) cooperates with 2-picolylamine unit (N3, N4) as a receptor bind Zn²⁺.