Medicinal herbs have long been used to treat a variety of ailments. India's traditional medicinal system relies heavily on the use of medicinal herbs. Plants have natural compounds that have antiproliferative properties against a variety of malignancies. Cancer is a disease that kills people and causes major defects in their bodies. There are numerous different types of cancer disorders that affect different organs in humans. There is no effective treatment for these types of cancers. In the present study, ethanolic extracts of Costus cosmosus have been investigated for its in-vitro antioxidant and cytotoxic potential against HepG2 cell lines. The ethanolic extracts of Costus cosmosus exhibited significant cytotoxic action against cell lines, as measured by cellular death in a dose-dependent manner, with the strongest effect occurring at higher doses. The findings suggested that the anticancer properties of ethanolic leaf extracts of Costus cosmosus could be linked to their flavonoid concentration. This research validates the cytotoxic potential of Costus cosmosus against HepG2 cell lines. © 2022 Elsevier B.V., All rights reserved.