In this study, a new series of tetrahydrobenzothiophene derivatives have been designed. Newly designed molecules have been synthesized through a medicinal chemistry route, and their characterization was done by using NMR and HR-MS techniques. Biological evaluation of the synthesized compounds has been done on Gram-negative and Gram-positive bacteria. The marketed antibiotics such as ciprofloxacin and gentamicin were used as controls. The <i>in vitro</i> evaluation results have shown that most of the targeted compounds exhibit good potency in inhibiting the growth of bacteria, including <i>E. coli</i> (MIC: 0.64-19.92 μM), <i>P. aeruginosa</i> (MIC: 0.72-45.30 μM), <i>Salmonella</i> (MIC: 0.54-90.58 μM) and <i>S. aureus</i> (MIC: 1.11-99.92 μM). In particular, compound 3b showed excellent activity with an MIC value of 1.11 μM against <i>E. coli</i>, 1.00 μM against <i>P. aeruginosa</i>, 0.54 μM against <i>Salmonella</i>, and 1.11 μM against <i>S. aureus</i>. From the results, a promising lead compound was identified for future development.