Breast cancer (BCa) is a type of malignancy; however, the exact mechanisms responsible for breast cancer have yet to be elucidated. Rhotekin 2 (RTKN2) is a member of the Rhotekin family. Previous studies demonstrated that RTKN2 is highly expressed in numerous tumors. Previous analysis of the The cancer genome altas (TCGA) database demonstrated that PRKN2 was overexpressed in BCa. However, RTKN2 is rarely reported in BCa and the mechanisms remain unclear. The aim of this study was to elucidate the effect of RTKN2 on the growth of breast cancer cells and investigate the mechanisms involved. Our analysis revealed high expression of RTKN2 in human BCa. The depletion of RTKN2 suppressed the growth of breast cancer cells. In addition, the knockout of RTKN2 restrained the progression of BCa. We also revealed that the knockdown of RTKN2 stimulated cell cycle arrest in BCa. Mechanistically, RTKN2 mediated the Wnt/β-catenin axis to affect the progression of breast cancer. In conclusion, RTKN2 promotes the growth and migration of breast cancer cells by mediating the Wnt/β-catenin axis.