Cu²⁺ is the third most prevalent transition metal ion in critical biological systems, although it is poisonous to humans. As a result of this, establishing a mechanism for selectively detecting the Cu²⁺ ion in an aqueous medium is crucial. A new triphenylamine-pyrenyl salicylic acid probe (Compound 3) was produced utilizing the Sonograshira reaction, the Suzuki cross-coupling process combined with a hydrolysis reaction for Cu²⁺ detection with a fluorescent turn-off mode. In the presence of Cu²⁺, Compound 3 operated as both a highly selective and highly sensitive fluorescent Cu²⁺ sensor in a 100% aqueous medium. Consequently, the fluorescence intensity of Compound 3 showed a strong linear relationship with the Cu²⁺ ion concentration in the 10 to 1000 pM range. The detection limit of the approach was 5.22 pM, which was less than the maximum Cu²⁺ level in drinking water, as suggested by the US Environmental Protection Agency of 19 µM. (EPA). Therefore, Compound 3 was successfully used to determine the concentration of Cu²⁺ in real samples.