Moringa oleifera is a well-known medicinal plant which has anti-cancer and other biological activities. This research aims to determine the cytotoxic and apoptotic effect of M. oleifera leave extract on the breast cancer (MCF7) cells. The extracts were prepared using hexane, dichloromethane, chloroform and n-butanol by fractionating the crude 80% methanol extract of the plant leaves. The cytotoxic effect of the extracts on MCF7 cells were determined using CellTiter 96® AQueous One Solution Cell Proliferation (MTS) assay. The apoptosis study was conducted using Annexin V-FITC analysis and confirmed by Western blotting using selected proteins, which are p53, Bax, cytochrome c and caspase 8. Our results showed that the dichloromethane (DF-CME-MOL) extract was selectively cytotoxic to MCF7 cells (5 μg/mL) without significantly inhibiting the non-cancerous breast (MCF 10A) cells. It had the highest selectivity index (SI) value of 9.5 among the tested extracts. It also induced early apoptosis and increased the expressions of pro-apoptotic proteins Bax, caspase 8 and p53 in MCF7 cells. Gas chromatography-mass spectrometry analysis (GC-MS) analysis showed that the major compounds found in DF-CME-MOL were benzeneacetonitrile, 4-hydroxy- and benzeneacetic acid, 4-hydroxy-, methyl ester among others that were detected. Thus, DF-CME-MOL extract was found to inhibit the proliferation of MCF7 cells by apoptosis induction, which is likely due to the activities of the detected phytochemical compounds of the extract.