Vernonia amygdalina Delile, coming from the Asteraceae tribe, contains active compounds that can treat breast cancer. This study examines the anticancer activity of Vernonia amygdalina Delile leaves, an active fraction of MCF-7/HER-2 breast cancer cells. Thin-layer chromatography determines the phytochemical screening. Cytotoxic and proliferation analyses were determined using the MTT method for the MCF-7/HER-2 breast cancer cell line. The cell cycle and apoptosis profiles were examined using flow cytometry. The results can be summarized in this study: Vernonia amygdalina Delile fraction contains a flavonoid with great potential for pharmacological activities, for instance, inhibiting the growth of cancer cells. The ethyl acetate fraction was more potent and cytotoxic on MCF-7/HER-2 cells (IC50 = 66 μg/mL) than extract ethanol (IC50 = 130 μg/mL). The ethylacetate fraction of Vernonia amygdalina Delile has been proven to inhibit cell proliferation by decreasing cell viability with an IC50 of 66 μg/mL concentration incubated for 24, 48, and 72 hrs with cell viability values of 64.46%, 61.67%, and 53.89%, respectively, compared to the ethanol extract IC50 of 130 μg/mL concentration with cell viability values of 56.0%, 50.19%, and 58.67%, respectively, which induced apoptosis and inhibited the cell cycle in the G2-M phase. To conclude, the ethyl acetate fraction of Vernonia amygdalina Delile can be used as an anticancer against the MCF-7/HER-2 cell line with an IC50 of 66 μg/mL, inhibiting cell proliferation and the cell cycle and inducing apoptosis activity in the MCF-7/HER-2 cell.