We demonstrate that bovine serum albumin (BSA)-coated mini gold nanorods (GNRs) chemically conjugated with a HER2-specific designed ankyrin repeat protein, DARPin_9-29, selectively accumulate in HER2-positive xenograft tumors in mice and lead to a strong reduction in the tumor size when being illuminated with near-infrared light. Here, ERBB2 is linked to neoplasm.