3-(1H-indol-3-yl)-1-(4-substitutedphenyl)prop-2-en-1-one derivatives (2a–i) and 2-[3-[3-(3-oxo-3-substitutedphenylprop-1-en-1-yl)-1H-indol-1-yl]-N-(4-sulfamoylphenyl)acetamide compounds (CS1–CS9) were designed and synthesized. The imidazole-derived original intermediate 2f showed greater effectiveness against the C6 rat glioma cell line. The compound CS1 and the original intermediates 2h, 2g, and 2i were the only other derivatives that showed substantial cytotoxic activity when compared to the reference drug tofacitinib. Among them, 2g, 2i, and 2h exhibited superior cytotoxic activity against the A549 lung cancer cell line. Compound 2f demonstrated cytotoxic effects on the C6 cancer cell line at 5 times the concentration of cisplatin and 20 times that of tofacitinib. Its selective cytotoxic effect on normal cells was also demonstrated at a concentration that was almost 66 times higher than that of the cancer line. Notably, the original chalcones (2f–2i) exhibited greater cytotoxic activity than the final compounds (CS1–CS9). The IC50 values of the compounds ranged from 0.103 to 1.375 mM. The most promising compound,2f, exhibited drug-likeness characteristics consistent with standard drug-likeness parameters. Compound 2f, 1-(4-(1H-imidazol-1-yl)phenyl)-3-(1H-indol-3-yl)prop-2-en-1-one, might be regarded as a potent and selective lead compound for the next drug design investigations.