Recent studies have reported that dishevelled-associated activator of morphogenesis 1 (DAAM1) is remarkably essential for mediating cell migration and invasion in breast cancer (BrCa). Nonetheless, the definite expression profile of DAAM1 in BrCa patients and the impact on metastasis of BrCa in vivo have not been explored up to now. The differential expression of DAAM1 in BrCa and adjacent tissues was assessed via immunohistochemistry (IHC) staining. The metastatic capacities of BrCa SUM-1315 cells were examined in BALB/c nude mice. Besides, the prognostic values of DAAM1 mRNA in BrCa were explored based on Kaplan-Meier (KM) plotter. The expression of DAAM1 protein was notably overexpressed in BrCa tissues compared with that in paired normal breast tissues. The high expression of DAAM1 in BrCa tissues was significantly associated with lymph-node metastasis. Furthermore, DAAM1 overexpression promoted the invasive capacity of BrCa cells and stimulated lung metastatic extent in vivo. We also found that overexpressed DAAM1 mRNA was significantly associated with poor relapse-free survival (RFS), overall survival (OS), distance-metastasis-free survival (DMFS), and post-progression survival (PPS). Our findings reveal that DAAM1 might be a novel therapeutic target to manage the deteriorated metastasis of BrCa and identified DAAM1 as a promising biomarker for unfavorable prognosis in BrCa patients.