The development of highly sensitive and selective detection techniques for the discrimination of relevant toxic benzenethiols and biologically active aliphatic thiols is of considerable importance in the fields of chemical, biological, and environmental sciences. In this article, we describe a new design of reaction-based fluorescent probe for discrimination of thiophenols over aliphaticthiols through intramolecular charge transfer pathways using N-butyl-4-amino-1,8-naphthalimide as a fluorophore, the strongly electron-withdrawing 2,4-dinitrobenzenesulfonamide group as a recognition unit, and 2,3-dihydroimidazo-[1,2-a] pyridine moiety as a linker. This rational design not only affords finely tunable spectroscopic properties by adding 2,3-dihydroimidazo-[1,2-a] pyridine moiety but also provides the chance to regulate the selectivity and sensitivity of the probe due to the formation of a new type of potentially reversible sulfonamide bond through 4-dimethylaminopyridine-like resonance. The developed probe displayed high off/on signal ratios, good selectivity, and sensitivity with a detection limit of 20 nM and a relative standard deviation of 1.7% for 11 replicate detections of 0.33 μM thiophenol and was successfully applied to the determination of thiophenols in water samples with quantitative recovery (from 94% to 97%) demonstrating its application prospect for thiophenols sensing in environmental and biological sciences.