Research on fluorescent chemosensors for the detection of metal ions has been well-documented. However, the sensing ability of a single molecule can also be utilized for different applications. In this study, the metal ion and gamma radiation detection with a single fluorescent molecular scaffold was investigated using a benzimidazole derivative containing a pyridine unit (BIPCl). BIPCl exhibited a selective, rapid, and stable "turn-off" fluorescence response toward Cu2+ ions at neutral pH. The Stern-Volmer analyses demonstrated a predominant static quenching mechanism (Ksv = 1.754 & times; 105 M- 1). The fluorescence titration experiments, ESI-MS data, BenesiHildebrand, and Job's plot analysis confirmed a 1:1 binding stoichiometry with the binding constant of 1.5 & times; 105 M- 1. The calculated Gibbs free energy (-29.53 kJ mol- 1) indicated the spontaneous nature of the BIPClCu2+ interaction. BIPCl can detect Cu2+ ions with a detection limit of 0.24 mu M. In addition, the effect of gamma radiation on the fluorescence response of BIPCl was investigated. BIPCl displayed an enhanced fluorescence after gamma irradiation in the range of 3.5-10 kGy due to the radiation-induced hydroxylation. Density Functional Theory (DFT) calculations, including ground and excited states, molecular orbital contributions, molecular electrostatic potential maps, electron density difference plots, and theoretical UV-Vis spectra, revealed that BIPCl exhibited an Intramolecular Charge Transfer (ICT) character, and the Cu2+ selectivity was driven by inhibition of ICT. The Fukui function was also employed to identify the radiation-induced hydroxylation sites of BIPCl. Consequently, this study thoroughly highlighted the dual-sensor capability of BIPCl for the detection of Cu2+ ions and gamma rays.