Breast cancer (BC) is characterized by the abnormal and rapid growth of breast epithelial cells, driven by various carcinogenic factors. Advances in understanding the signaling pathways and molecular mechanisms involved in BC progression have facilitated the development of small molecule inhibitors for its treatment. Significant progress has been made in creating inhibitors that target the PI3K/AKT/mTOR signaling pathway. Current clinical research focuses on compounds such as GDC-0077 and NVP-BKM120, advancing into phase II/III clinical trials. Preclinical drugs like NVP-CLR457, AZD6482, PF-06843195, and GDC-0326 show promising potential for further optimization and entry into BC clinical trials. This review aims to provide an overview of the clinical and preclinical development of small molecule inhibitors for various molecular subtypes of BC, emphasizing their structural composition, therapeutic outcomes, and mechanisms of action. Additionally, we highlight key targets and pathways involved in BC pathogenesis, offering essential insights for the design of effective therapeutic agents for breast cancer.