Breast cancer is the second most common cancer among women in the United States. The American Cancer Society's estimated that 281,550 new cases of invasive breast cancer will be diagnosed in American women in 2021. In addition, some 49,290 new cases of ductal carcinoma in situ (DCIS) will be diagnosed and approximately 43,600 women will die from breast cancer. Advances in our knowledge of breast cancer pathophysiology and its clinical implications have led to the development of new therapies and opportunities to tailor chemotherapy based on tumor biology and/or tumor burden. New and emerging therapies for breast cancer include cyclin-dependent kinase 4/6 (CDK4/6) inhibitors, programmed death receptor-1 (PD-1) /PD-1 inhibitors, poly ADPribose polymerase (PARP) inhibitors, monoclonal antibodies, tyrosine kinase inhibitors (TKIs), and vaccines that stimulate immune response targeting tumor-associated antigens. New Drug approvals in recent years include the PI3Kα-specific inhibitor alpelisib, ado-trastuzumab emtansine, fam-trastuzumab-deruxtecan-nxki, combination therapy with atezolizumab and nab-paclitaxel, tucatinib, margetuximab (anti-HER2 mAb), and sacituzumab govitecan-hziy for metastatic triple-negative breast cancer. Understanding the optimal use of these novel therapies based on the breast cancer diagnosis is critical for individualizing patient therapy and improving outcomes.