In this study, synthesis, characterization, and biological activities of 30 original 5-methyl/ethylsulfonyl-2-(4-(4-substituted piperazine/piperidine)acetamido)phenylbenzoxazole derivatives were investigated. The structures of the final compounds were characterized using 1H NMR, 13C NMR, and mass spectroscopy. Then, all the newly synthesized compounds were screened for their antimicrobial activities against S. aureus ATCC 29213, E. faecalis ATCC 29212, E. coli ATCC 25922, P. aeruginosa ATCC 27853, C. albicans ATCC 10231, and their drug-resistant isolates by applying MIC analyses using ampicillin, gentamicin, vancomycin, ciprofloxacin, and fluconazole as standards. Microbiological results showed that N17, N18, N20, N25–N28, and N30–N32 exhibited activity against VREF at 32 µg/mL, comparable to ampicillin and vancomycin. The interactions of the compounds on the DNA gyrase enzyme were evaluated by molecular docking (PDB: 4KTN). Using DFT/B3LYP theory and the 6-311G(d,p) basis set, HOMO–LUMO orbital energies and other electronic characteristics obtained from these energies and MEP analysis were carried out. These results were then correlated with experimental data. Furthermore, computational prediction was performed to predict the in silico ADMET properties of all compounds.