Rosmarinic acid is a natural polyphenolic compound that is found in different plant species and used for different medicinal purposes. This study aimed to investigate the chemo-preventive effect of rosmarinic acid and evaluate its antitumor efficacy alone or in combination with Paclitaxel in breast cancer mice model. Ehrlich induced mice mammary solid tumor model was used in the study. Mice were treated with oral rosmarinic acid and intraperitoneal Paclitaxel. Inflammation, angiogenesis, and apoptosis were checked. Enzyme linked immunosorbent assay (ELISA), quantitative real time PCR, and immunohistochemical methods were performed. Rosmarinic acid used prior to tumor induction suppressed NF-κB, TNF-α, vascular endothelial growth factor (VEGF) serum levels, and VEGF receptors. It also triggered apoptosis by restoring the levels of P53, Bcl-2, Bax, and caspase-3. Furthermore, in Ehrlich solid tumor mice, rosmarinic acid, and/or Paclitaxel significantly suppressed tumor growth with an increase in apoptotic markers P53 and Caspase-3 levels, and suppressed the Bcl2/Bax ratio.Rosmarinic acid exerted chemo-preventive and therapeutic potential alone or in combination with Paclitaxel. Moreover, rosmarinic acid targets numerous signaling pathways associated with breast cancer.