Flos Sophorae, the dried flower bud of Sophora japonica L, possesses anti-inflammatory properties, prevents and treats blood capillary and hypertension diseases and can also be used as a hemostat. However, the effect of Flos Sophorae on breast cancer invasion is unknown. Matrix metalloproteinase-9 (MMP-9), which degrades the extracellular matrix, is a major component in cancer cell invasion. In this study, we investigated the inhibitory effect of Flos Sophorae extract (FSE) on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced Matrix metalloproteinase-9 (MMP-9) expression and cell invasion, as well as the molecular mechanisms involved in Michigan Cancer Foundation-7 (MCF-7) cells. FSE inhibited the TPA-induced transcriptional activation of nuclear factor-kappa B (NF-${kappa}B$). These results indicate that FSE-mediated inhibition of TPA-induced MMP-9 expression and cell invasion involves the suppression of NF-${kappa}B$ pathway in MCF-7 cells. Thus, FSE may have therapeutic potential for controlling breast cancer invasiveness.