Photo-activatable carbon monoxide (CO)-releasing molecules (photoCORMs), have recently provided help to identify the salutary effects of CO in human pathophysiology. Among them notable is the ability of CO to sensitize chemotherapeutic-resistant cancer cells. Findings from our group have shown CO to mitigate drug resistance in certain cancer cells by the inhibition of cystathionine β-synthase (CBS), a key regulator of redox homeostasis in the cell. Diminution of the antioxidant capacity of cancer cells leads to sensitization to reactive oxygen species-producing drugs like doxorubicin and paclitaxel upon cotreatment with CO as well as in mitigating the drug effects of cisplatin. We hypothesize that the development of CO delivery techniques for coadministration with existing cancer treatment regimens may ultimately improve clinical outcomes in cancer therapy.