In the tumor microenvironment (TME) of breast cancer, tumor-associated macrophages (TAMs) predominantly exhibit a pro-tumor M2 phenotype. These M2 TAMs significantly exacerbate breast cancer malignant progression through multiple mechanisms: they secrete growth factors and cytokines to promote the proliferation, invasion and migration of tumor cells; they facilitate tumor metastasis by inducing angiogenesis and remodeling the extracellular matrix; and they mediate the resistance of tumor cells to chemotherapy, targeted therapy and immunotherapy by providing survival signals, etc., leading to drug resistance. Consequently, TAMs are pivotal drivers of breast cancer initiation, progression, metastasis, and therapy resistance. With its excellent targeting, drug-carrying diversity and microenvironmental response properties, the nano-delivery system provides a new strategy for targeting and regulating the phenotypic polarization of TAMs by remodeling the inflammatory environment, modulating oxidative stress and immune signaling networks, and regulating the metabolic reprogramming of glucose, lipids, and amino acids, making it a key research direction for reversing TME, which has an important potential for clinical translation. This review systematically summarizes the critical impact of TAM phenotypic polarization on breast cancer pathogenesis, metastasis, and drug resistance, alongside nano delivery-based strategies for TAM reprogramming and the underlying molecular network mechanisms they regulate, aiming to provide new insights for the precision treatment of breast cancer.