Herein, we report the experimental evaluation of the antimicrobial activity of seventeen new (Z)-methyl 3-(4-oxo-2-thioxothiazolidin-5-ylidene)methyl)-1H-indole-2-carboxylate derivatives. All tested compounds exhibited antibacterial activity against eight Gram-positive and Gram-negative bacteria. Their activity exceeded those of ampicillin as well as streptomycin by 10–50 fold. The most sensitive bacterium was En. Cloacae, while E. coli was the most resistant one, followed by M. flavus. The most active compound appeared to be compound 8 with MIC at 0.004–0.03 mg/mL and MBC at 0.008–0.06 mg/mL. The antifungal activity of tested compounds was good to excellent with MIC in the range of 0.004–0.06 mg/mL, with compound 15 being the most potent. T. viride was the most sensitive fungal, while A. fumigatus was the most resistant one. Docking studies revealed that the inhibition of E. coli MurB is probably responsible for their antibacterial activity, while 14a–lanosterol demethylase of CYP51Ca is involved in the mechanism of antifungal activity. Furthermore, drug-likeness and ADMET profile prediction were performed. Finally, the cytotoxicity studies were performed for the most active compounds using MTT assay against normal MRC5 cells.