The vibrations were attributed to 5-chloro-2-mercaptobenzimidazole using FTIR and FT-Raman spectroscopy. The optimized geometrical parameters, IR intensity, and the Raman activity of the vibrational bands were estimated using the Becke three-parameter Lee-Yang-Parr functional and the 6-311++G(d,p) level of theory. These findings are compared with the experimental data. The molecule’s HOMO-LUMO energy gap is found to be 4.418 eV. UV-Vis analysis reveals that the π→π* transition, which happens when electron density shifts from nitrogen, sulfur, and chlorine atoms in the molecule, to the electrons of the C-C bonds of the ring. Total density of states was used to assess the molecular orbital contributions. There are 47α and 47β electrons totaling 94 electrons in the DOS spectrum. NBO investigations indicate that a considerable stabilizing energy of 30.37 and 30.90 Kcal/mol was revealed by the lone pair transition of N1 and N3 atoms to π*(C7-C8) and π*(C4-C9). The more electrophilic region, as seen by the red zone in MEP mapping, lies in the vicinity of the nitrogen and sulfur atoms. The molecule’s hydrogen atoms are found in the blue nucleophilic area. The theoretical chemical shifts for 1H and 13C NMR ranged from 7.03 to 8.23 ppm and 113.10 to 207.31 ppm, respectively. The docking research showed that the molecule attached to protein 1AQU with a greater binding energy of −6.8 Kcalmol−1. The cytotoxicity of the sample was evaluated against a MCF-7 cell line (IC50 = 16.54 µg/ml) and exhibited a good breast cancer action. In addition, ADMET prediction has been used to estimate the medicinal applicability of the chemical.