Zingiber zerumbet (L.) Roscoe ex Sm. (Zingiberaceae) is used in an extensive range of conventional medicine practices. This study demonstrates the chemical constituents of the rhizome extract of Z. zerumbet and evaluates its antiradical, antiproliferative and apoptosis-inducing potential against breast cancer cells. Gas Chromatography-Mass Spectrometry (GC-MS) analysis identified zerumbone (94.88 ± 0.02) to be the main component of the methanol extract along with humulene epoxide (3.05 ± 0.06) and caryophyllene oxide (2.07 ± 0.04). The extract exhibited notable antiradical activity with IC50 value of 261.66 ± 0.20 and 159.45 ± 0.15µg/mL for DPPH and ABTS assays respectively. While the reducing power assay indicated effective activity in the range, 200–500µg/mL. Moreover, cell viability assay exhibited MCF-7 cells to be the most sensitive among the cell lines examined. DNA fragmentation analysis and Annexin V-Fluorescein Isothiocyanate/propidium iodide (Annexin V-FITC/PI) dual staining confirmed the induction of apoptosis in MCF-7 cells. The changes in nuclear morphology were further validated using 4′,6-diamidino-2-phenylindole (DAPI) staining. Additionally, the cell migration assay presented the anti-metastatic potential of the extract. Findings of this study demonstrated that Z. zerumbet exerts cytotoxic and apoptosis induction effects against MCF-7 cells, indicating its potential significance for future preclinical studies in breast cancer.