Integration of diagnostic and therapeutic modalities into a single nanoplatform can play an important role in personalized cancer therapy. In this work, an all-in-one theranostic nanoplatform (HPCT nanomicelles) for breast cancer was fabricated, composed of the synthetic polymer hyaluronan-b-poly(ε-caprolactone) (HA-PCL), drug curcumin (Cur) and adjuvant tocopheryl polyethylene glycol succinate (TPGS). HPCT nanomicelles presented adequate drug loading efficiency, excellent stability, and attractive hyaluronidase-sensitive release features. Imaging agent radionuclide ^99mTc was loaded into HPCT nanomicelles (denoted as ^99mTc-HPCT nanomicelles) and in vivo SPECT/CT imaging verified the HA-based nanomicelles could actively target breast cancer in mice. In vivo anti-tumor pharmacodynamic studies indicated that HPCT nanomicelles exhibited desirable anti-tumor efficacy with favorable biosafety. ^99mTc-HPCT nanomicelles, integrating imaging and therapeutic modalities, have the promising potential to be an all-in-one theranostic nanoplatform for breast cancer.