The antitumor property of steroids in sweet potato ( Ipomoea batatas L.) remains poorly understood. Herein, we investigated the anticancer effect on breast carcinoma of daucosterol linoleate (DL), a steroid isolated from sweet potato. DL inhibited the cell viability of estrogen receptor (ER)-positive MCF-7 breast cancer cells at an IC50 value of 53.27 ± 9.02 μg/mL, while the effect was modest in ER-negative MDA-MB-231 breast cancer cells. Flow cytometry indicated that the DL-induced apoptosis in MCF-7 cells is dose-dependent. However, DL inhibited tumor growth and tumor weight at 100 mg/kg in MCF-7 xenograft nude mice. DL diminished the expression of Bcl-xl, Bcl-2, and XIAP, while increasing Bax, Bad, and activated caspase-dependent apoptosis in tumor tissues. Furthermore, DL inactivated the upstream Pi3k/Akt/NF-κB pathway. In the 4T1 spontaneous metastasis model, DL blocked metastasis progression, decreased the number of visible metastasis foci and inhibited metastasis size distribution in lung tissue. Further studies showed that DL suppressed VEGF, MMP 2, and MMP 9 expression in both tumor and lung tissues. From these results, we can assume that DL is a potential adjuvant therapy for ER-positive breast cancer patients.