Objective To investigate how flavokawain B (FKB) affects the proliferation and migration of triple-negative breast cancer (TNBC) cells by downregulating the androgen receptor (AR). Methods The expression of AR in breast cancer and normal tissues was analyzed using the GEPIA2 database. Expression of estrogen receptor (ER), human epidermal growth factor receptor 2 (HER2), progesterone receptor (PR), and AR was detected in six breast cancer cell lines (SUM159PT, MCF-7, T47D, BT474, Hs-578T, and MDB-MA-231) by Western blotting. The effect of FKB (0, 10, 20, 30, 40, 50, 60 μmoL/L) treatment of 24, 48, and 72 h on the proliferative activity of SUM159PT breast cancer cells was assessed using the CCK-8 assay under normal or androgen deprivation conditions. The mRNA and protein of AR expression was measured by qRT-PCR and Western blotting after 30 μmoL/L FKB treatment of SUM159PT cells for 0, 4 and 8 h. SUM159PT cells were set as control group (treatment with 0.1% DMSO), dihydrotestosterone (DHT) group (treatment with 10 nmol/L DHT), FKB group (treatment with 15 μmol/L FKB), DHT+FKB group (treatment with 10 nmol/L DHT and 15 μmol/L FKB), AR antagonist enzalutamide (ENZA) group (treatment with 40 μmol/L ENZA), and DHT+ENZA group (treatment with 10 nmol/L DHT and 40 μmol/L ENZA) under androgen deprivation conditions. Cell proliferation, migration, and colony formation abilities in the above groups were determined using the CCK-8 method, Transwell assay, and clone formation test. Western blotting was also used to detect the expression levels of EMT-related proteins (N-cadherin, Occludin, Vimentin) and AR protein. Results AR mRNA expression level was significantly higher in breast cancer tissue than in normal breast tissue (P<0.05). AR was expressed at comparable levels in five different breast cancer cell lines (SUM159PT, MCF-7, T47D, BT474, and Hs-578T) in addition to MDB-MA-231. FKB can downregulate AR mRNA and protein levels (P<0.05). Western blotting results showed that DHT could upregulate AR protein levels in SUM159PT cells, but FKB could prevent the DHT-induced upregulation of AR protein levels (P<0.05). FKB and ENZA decreased SUM159PT cell proliferation and migration and DHT-mediated cell proliferation and migration (P<0.05). FKB and ENZA can reduce N-cadherin and Vimentin protein levels and counteract DHT-induced increases in N-cadherin and Vimentin protein levels (P<0.05). In addition, FKB may increase Occludin expression and counteract the DHT-induced decrease in Occludin protein expression (P<0.05). Conclusion Flavokawain B could inhibit the proliferation, migration, and clonogenic ability of TNBC cells by regulating AR expression.