The pharmacological application of nanodevices and systems is a rapidly emerging nanotechnology that is raising new possibilities in the diagnosis and therapy of different diseases. Nanotechnology has been providing promising tools for chemotherapy especially in cancer treatment. Nanotechnology deals with physical and biochemical properties of nanoparticles in the clinical application of drugs. Targeted nanoparticle drug delivery is intended to reduce the side effects of anticancer drugs with both decreases in consumption and treatment expenses, which are the major hurdles in conventional cancer treatment. The characteristic small size and special coating of nanoparticles facilitates the delivery of hydrophobic anticancer drugs to specific sites with reduced opsonization by defense mechanisms of the body. One of the vast applications of nanotechnology is the diagnosis, treatment, and prevention of breast cancers. Breast cancer is associated with high morbidity and mortality and is the second leading cause of death in Western countries. A large number of nanoparticles have been developed, specifically targeting metastasized tumors of the breast. The present review focuses on the application of different types of nanoparticles including gold, polymeric, and magnetic nanoparticles in the treatment of breast cancer.