Breast cancer (BC) is the most common malignancy in women and is one of the leading causes of cancer-associated deaths. The analysis of data obtained from online databases revealed that RILPL2 expression in BC tissues is lower than that in normal tissues, and that RILPL2 upregulation is correlated with prolonged recurrence-free survival (RFS), overall survival (OS), and distant metastasis-free survival (DMFS). However, the function of RILPL2 in tumor proliferation and metastasis remains unclear. In this study, we demonstrated that RILPL2 had lower expression in BC tissues than in adjacent normal tissues, and that RILPL2 expression was significantly negatively correlated with tumor size, histological grade, and lymph node metastasis. Univariate analysis showed a positive correlation between RILPL2 and estrogen receptor (ER) expression and a negative correlation between RILPL2 and human epidermal growth factor receptor 2 (HER2) expression. Overexpression of RILPL2 inhibited BC cell proliferation and metastasis in vitro and in vivo. In addition, the interaction of exogenous RILPL2 with TUBB3 resulted in the downregulation of BC cell proliferation and migration and upregulation of PTEN expression by promoting destabilization of TUBB3. Furthermore, RILPL2 could reverse BC cell resistance to taxotere-mediated apoptosis by regulating the TUBB3/PTEN/AKT pathway. In conclusion, these results suggest that RILPL2 could be a novel biomarker for the diagnosis and treatment of BC.