In this study, we aimed to develop anti-human epidermal growth factor receptor 2 (HER2) indocyanine green (ICG)-doxorubicin (DOX)-encapsulated polyethylene glycol-poly(lactic-co-glycolic acid) diblock copolymeric nanoparticles (HIDPPNPs) to explore the co-administration of phototherapy and chemotherapy for HER2-overexpressing breast cancer, a highly aggressive and medicine-resistant breast carcinoma. This evidence concerns the gene ERBB2 and breast cancer.