We find that FMOD is essential in promoting breast cancer metastasis, FMOD expression is regulated positively by the Wnt/β-catenin signaling pathway, wherein the β-catenin/TCF4/LEF1 complex binds to the FMOD promoter for its transcription, and Aspirin inhibits breast cancer metastasis by attenuating the Wnt/β-catenin pathway and suppressing FMOD expression, evidently via inhibiting HDAC6 deacetylation of β-catenin. Here, FMOD is linked to breast cancer.