Breast cancer (BC) is the most prevalent malignancy in women. The main treatment for BC is surgery and chemotherapy. Generally, the chemotherapeutic drugs used for treatment cause numerous side effects. Substances derived from natural products have proven to exhibit anti-cancer effects without causing side effects. For instance, biochannin A found in cabbage and cauliflower reduced the growth of estrogen dependent MCF 7 cells. Another example is curcumin present in turmeric exhibits anti-proliferative and inhibitory effect against BC. The active compound of Nigella sativa is thymoquinone. The oil extracted from Nigella sativa reduced blood pressure. Nigella sativa exerts anti-pyritic, anti-inflammatory, and anti-microbial activity. Thymoquinone is found in seeds of Nigella sativa. Thymoquinone is a promising anti-neoplastic, anti-carcinogenic, anti-proliferative agent. In this chapter, the authors emphasize the anticancer potential of Nigella sativa and its derivatives and the mechanism of action against BC.