Grapefruit mint (Mentha suaveolens × piperita) is a hybrid, perennial, and aromatic plant widely cultivated all over the world and used in the food, cosmetics, and pharmaceutical industries mostly for its valuable essential oil. Herein, we evaluated the anticancer activity of the grapefruit mint essential oil, cultivated in Iran. For the chemical composition analysis of essential oil, GC-MS was used. MTT assay was utilized for assessing the cytotoxic activity of the essential oil. The type of cell death was determined by annexin V/PI staining. Essential oil effect on the expression of maternally expressed gene 3 (MEG3), a regulatory lncRNA involved in cell growth, proliferation, and metastasis, was studied using qRT-PCR. Linalool (43.9%) and linalool acetate (40.1%) were identified as the dominant compounds of essential oil. Compared with MCF-7, the MDA-MB-231 cells were more sensitive to essential oil (IC50 = 7.6 µg/ml in MCF-7 and 5.9 µg/ml in MDA-MB-231 after 48 h). Essential oil induced cell death by apoptosis. Wound healing scratch assay confirmed the anti-invasive effect of essential oil. In addition, essential oil upregulated the tumor suppressor MEG3 in breast cancer cells. These results provide new insights into grapefruit mint essential oil potential application as an anticancer adjuvant in combination treatments for breast cancer patients.