A highly sensitive fluorescent probe (1) based on styrylcyanine dye for Cu²⁺ and Pb²⁺ has been developed. Probe 1 exhibited fluorescent turn-off sensing ability to Cu²⁺. On the other hand, 1 displayed ratiometric fluorescent response towards Pb²⁺ with a distinct fluorescent color change from blue to orange. The ¹H NMR titrations revealed that the fluorescent response of 1 to Cu²⁺ and Pb²⁺ is triggered by the interaction of the pyridine unit and the metal ion. Detection limits of 1 to Cu²⁺ or Pb²⁺ were calculated as 1.24 and 3.41 × 10⁻⁶ M, respectively, by standard deviation and linear fitting. Furthermore, 1 can also be used as a sensor for detection of Cu²⁺ and Pb²⁺ in a test strip.