Immunotherapy has emerged as a promising treatment option for breast cancer, particularly in triple-negative breast cancer (TNBC). Despite traditional views that breast cancer is immunologically "cold," recent clinical trials have shown that immunotherapy can be effective in certain patients. Breast cancer is categorized into subtypes, including HR+ HER2−, HER2+, and TNBC, each requiring tailored treatment strategies. Immunotherapy, particularly checkpoint inhibitors (ICIs), has shown efficacy in TNBC, especially when combined with chemotherapy. Pembrolizumab, an ICI, has been approved for use in TNBC, both in neoadjuvant and advanced settings. Trials have demonstrated improved pathologic complete response (pCR) rates and survival outcomes when pembrolizumab is combined with chemotherapy. Biomarkers such as PD-L1 combined positive score (CPS), tumor mutation burden (TMB), and tumor-infiltrating lymphocytes (TILs) are being investigated for patient selection. In HR+ HER2− breast cancer, ICIs have shown promise as adjuncts to neoadjuvant chemotherapy, improving outcomes in high-risk patients. In HER2+ breast cancer, ICIs are being explored in combination with HER2-targeted therapies. Other immunotherapeutic approaches, including CAR-T cells, oncolytic viruses, and vaccines, are also under investigation. Challenges remain in identifying effective biomarkers and managing the toxicities associated with immunotherapy. Future research aims to refine immunotherapy delivery, elucidate resistance mechanisms, and explore novel combination therapies to improve outcomes for breast cancer patients.Immunotherapy has emerged as a promising treatment option for breast cancer, particularly in triple-negative breast cancer (TNBC). Despite traditional views that breast cancer is immunologically "cold," recent clinical trials have shown that immunotherapy can be effective in certain patients. Breast cancer is categorized into subtypes, including HR+ HER2−, HER2+, and TNBC, each requiring tailored treatment strategies. Immunotherapy, particularly checkpoint inhibitors (ICIs), has shown efficacy in TNBC, especially when combined with chemotherapy. Pembrolizumab, an ICI, has been approved for use in TNBC, both in neoadjuvant and advanced settings. Trials have demonstrated improved pathologic complete response (pCR) rates and survival outcomes when pembrolizumab is combined with chemotherapy. Biomarkers such as PD-L1 combined positive score (CPS), tumor mutation burden (TMB), and tumor-infiltrating lymphocytes (TILs) are being investigated for patient selection. In HR+ HER2− breast cancer, ICIs have shown promise as adjuncts to neoadjuvant chemotherapy, improving outcomes in high-risk patients. In HER2+ breast cancer, ICIs are being explored in combination with HER2-targeted therapies. Other immunotherapeutic approaches, including CAR-T cells, oncolytic viruses, and vaccines, are also under investigation. Challenges remain in identifying effective biomarkers and managing the toxicities associated with immunotherapy. Future research aims to refine immunotherapy delivery, elucidate resistance mechanisms, and explore novel combination therapies to improve outcomes for breast cancer patients.