Identification of novel natural treatment to combat cancer is a current need. This study was aimed at assessing the anticancer effects of ethanol‐extracted Cameroonian propolis (EEP). The antitumor effect of EPP was evaluated in vitro by measuring; cell viability, cell cycle, cell death mechanism, cell migration/invasion, reactive oxygen species (ROS), mitochondrial potential (ΔΨm), caspase activity, and apoptosis‐regulating proteins (Bcl‐2 and Bcl‐XL) in cell lines. In vivo, the effect of EEP against 7,12 dimethylbenz(a)anthracene (DMBA)‐induced breast tumorigenesis in rats was assessed. EEP was found to induce cytotoxicity against ER negative MDA‐MB‐231 breast cancer cells by activating apoptosis through ROS‐mediated mitochondrial pathway. The extract equally triggered caspase‐3 and caspase‐9, increment of ROS level, disruption of ΔΨm and down‐regulation of Bcl‐XL and Bcl‐2 proteins. Besides, EPP prevented migration and invasion activities by inhibiting MMP‐2 activity. At all doses it prevented breast tumor incidence (20% in EEP 150 mg/kg vs 70% in DMBA) as well as tumor burden. Tumor sections from EEP‐treated rats showed middle proliferation of mammary ducts with weak inflammatory responses. In summary, Cameroonian propolis exhibited antimammary tumor effects via the intrinsic pathway of apoptosis.