Metal complexes have gained significant attention as potential anti-cancer agents. The anti-cancer activity of Co(phen)(MeATSC)•1.5HO•CHOH (where phen = 1,10-phenanthroline and MeATSC = 9-anthraldehyde-(4)-methylthiosemicarbazone) and [Cu(acetylethTSC)Cl]Cl•0.25CHOH (where acetylethTSC = -ethyl-2-[1-(thiazol-2-yl)ethylidene]hydrazinecarbothioamide) was investigated by analyzing DNA cleavage activity. The cytotoxic effect was analyzed using CCK-8 viability assay. The activities of caspase 3/7, 9, and 1, reactive oxygen species (ROS) production, cell cycle arrest, and mitochondrial function were further analyzed to study the cell death mechanisms. Complex induced a significant increase in nicked DNA. The IC values of complex were 17.59 μM and 61.26 μM in cancer and non-cancer cells, respectively. The IC values of complex were 5.63 and 12.19 μM for cancer and non-cancer cells, respectively. Complex induced an increase in ROS levels, mitochondrial dysfunction, and activated caspases 3/7, 9, and 1, which indicated the induction of intrinsic apoptotic pathway and pyroptosis. Complex induced cell cycle arrest in the S phase, ROS generation, and caspase 3/7 activation. Thus, complex induced cell death in the breast cancer cell line activation of oxidative stress which induced apoptosis and pyroptosis while complex induced cell cycle arrest through the induction of DNA cleavage.