In the present study, a series of multipotent antioxidants (MPAOs), namely sulfur-containing BHT (S-BHT), derivatives were rationally designed and synthesized, and their inhibitory activities against free radicals and human cancer cell lines, HT29 (colon cancer) and MCF7 (breast cancer) were further evaluated. The experimental results showed that the Six out-of-eight S-BHT compounds had excellent antioxidant activity against DPPH radical with major enhancement compared to BHT. Among them, compounds 2b, 2a and 3b attained over 45% lower IC₅₀ values than BHT. _{In vitro} cytotoxicity, MTT assay was carried out using two human cancer cell lines, HT29 (colon cancer) and MCF7 (breast cancer) in addition to their non-tumorigenic counterparts to explore selectivity. In line with antioxidant activity, compounds 2a and 2b displayed the highest cytotoxicity effect on both cancer types. Interestingly, 2b not only exhibited superior cancer inhibition but also scored high selectivity index (SI = 5.2, 12.5) in colon and breast tissues, respectively, exceeding that of the standard chemotherapeutic drugs used 5-Fluorouracil (5-FU) and Tamoxifen (Tmx), with lower IC₅₀ values. The results indicated that the symmetric S-BHT derivatives were significantlyenhanced by the antioxidant potency and their ability as useful and promising selective anticancer agents.