Breast cancer is the leading cause of cancer death in women worldwide which is closely related to metastasis. But the exact molecular mechanism on metastasis is still not fully understood; we now report that both MRTF-A and STAT3 play important role in breast cancer migration of MDA-MB-231 cells. Moreover, MRTF-A and STAT3 synergistically increased MDA-MB-231 cell migration by promoting the expression of migration markers Myl-9 and Cyr-61. Importantly, we identified a detailed molecular mechanism of MDA-MB-231 cell migration controlled via physical interaction between MRTF-A and STAT3, which synergistically promote the transactivity of the migration marker Myl-9 and Cyr-61 by CArG box binding. Interestingly, the two signaling pathways RhoA-MRTF-A and JAK-STAT3 across talk to regulate MDA-MB-231 cell migration. Our data thus provide important and novel insights into the roles of MRTF-A and STAT3 in regulating MDA-MB-231 cell migration.