The locoregional recurrence of breast cancer after tumor resection represents several clinical challenges, and conventional post-surgical adjuvant therapeutics always bring about significant systemic side effects. Thus, the local therapy strategy has received considerable interest in breast cancer treatment, and hydrogels can function as ideal platforms due to their remarkable properties such as good biocompatibility, biodegradability, flexibility, and multifunctionality. The nano-hydrogel composites can further incorporate the advantages of nanomaterials into the hydrogel system, to fabricate hierarchical structures for stimulating controlled multi-stage release of different therapeutic agents and improving the synergistic effects of combination therapy. In this review, the problems of clinical treatments of breast cancer and properties of hydrogels in current biomedical applications are briefly overviewed. The focus is on recent advances in local therapy based on nano-hydrogel composites for both monotherapy (chemotherapy, photothermal and photodynamic therapy) and combination therapy (dual chemotherapy, photothermal chemotherapy, photothermal immunotherapy, radio-chemotherapy). Moreover, the challenges and perspectives in the development of advanced nano-hydrogel systems are also discussed.