Breast　cancer　has　the　highest　incidence　and　mortality　in　the　female　population.　Forkhead　box　M1　(FOXM1)　known　as　a　transcription　factor　is　upregulated　and　associated　with　poor　prognosis　in　a　variety　of　cancers.　However,　the　molecular　mechanisms　of　FOXM1　on　breast　cancer　progression　are　poorly　understood.　In　this　study,　we　found　that　FOXM1　was　up-regulated　in　breast　cancer.　FOXM1　promoted　cell　proliferation,　clonal　formation,　and　migration　capacity　in　triple　negative　breast　cancer　by　increasing　transcriptional　activity　of　YAP1.　FOXM1　also　maintained　cell　stemness　via　the　Hippo　pathway.　The　YAP1-TEAD　binding　inhibitor　Verteporfin　reduced　the　transcription　level　of　OCT4　and　NANOG　but　the　Hippo　pathway　activator　XMU-MP-1　could　increase　the　transcription　level　of　OCT4　and　NANOG.　In　summary,　our　findings　indicated　that　FOXM1　promoted　breast　cancer　progression　through　the　Hippo　pathway,　and　it　was　suggested　a　new　strategy　to　treat　breast　cancer.