Pomegranate (Punica granatum L.) is known to possess pharmacological activities, such as antioxidant and anticancer. In this study, we evaluated the antioxidant potency of a methanolic pomegranate fruit peel extract (PPE) and the relation with its antiproliferative and apoptotic effects on MCF-7 human breast cancer cells. Total phenolic content and antioxidant activity of PPE were determined using the Folin-Ciocalteau and the 2,2-diphenyl-l-picrylhydrazyl free radical methods, respectively. Phenolic acids present in the extract were characterized by a reverse-phase high-performance liquid chromatography (HPLC) method. Cell proliferation was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay. The apoptotic effects were determined by in situ Tdt-mediated dUTP nick end-labeling assay, and Bax/Bcl-2 mRNA expression levels were measured by reverse transcription-polymerase chain reaction. The extraction yield as a percentage of plant material was 37.97% (wt/wt), and total phenolic content was 331.28 mg of gallic acid equivalents/g of extract. According to HPLC analysis, the most abundant phenolic acid detected in the extract was ellagic acid. MCF-7 cell proliferation decreased depending on PPE concentration (25, 50, 100, 200, and 300 μg/mL) and incubation times (24, 48, and 72 hours). After 48 and 72 hours, the apoptotic cell numbers were significantly increased at 100, 200, and 300 μg/mL PPE concentrations. In addition, expression of the pro-apoptotic gene Bax was increased, and that of the anti-apoptotic gene Bcl-2 was decreased after 200 and 300 μg/mL PPE treatment for 48 and 72 hours. Because PPE reduced cell proliferation and induced apoptosis on MCF-7 cancer cells, we believe that PPE has important antioxidant and apoptotic effects.