The homeobox family genes are often dysregulated in various cancer types. In particular, HOXB7 overexpression contributes to cancer progression by promoting epithelial to mesenchymal transition, anti-cancer drug resistance, and metastasis of breast, hepatocellular and gastric cancer. Although the relationship between HOXB7 and cancer progression has been described, the role of HOXB7 in cancer initiation is unclear. In this study, we showed that HOXB7 overexpression induced oncogenic transformation in vitro and in vivo through the activation of JAK-STAT signaling and enhanced the expression of ERBB2 in NMuMG cells. In public data sets, HER2-positive breast cancer highly expressed HOXB7, the expression of which was correlated with poor prognosis in breast cancer cohorts. Furthermore, the amplification of HOXB7 on 17q23.32 was found to be a potential clinical diagnostic marker.