ObjectiveTriple negative breast cancer (TNBC) is the most invasive breast cancer subtype enriched with cancer stem cells. TNBCs do not express estrogen, progesterone, or human epidermal growth factor receptor 2 (HER2) receptors, making them difficult to be targeted by existing chemotherapy treatments. In this study, we attempted to identify the effects of combined cisplatin andClinacanthus nutanstreatment on MDA-MD-231 and MDA-MB-468 breast cancer cells, which represent TNBC subtypes.MethodsThe phytochemical fingerprint ofC. nutansethanolic leaf extract was evaluated by LC–MS/MS analysis. We investigated the effects of cisplatin (0–15.23 μg/mL),C. nutans(0–50 μg/mL), and a combination of cisplatin (3.05 μg/mL) andC. nutans(0–50 μg/mL), on cell viability, proliferation, apoptosis, invasion, mRNA expression in cancer stem cells (CD49f, KLF4), and differentiation markers (TUBA1A, KRT18) in TNBC cells. In addition, we also studied the interaction between cisplatin andC. nutans.ResultsDerivatives of fatty acids, carboxylic acid ester, and glycosides, were identified as the major bioactive compounds with potential anticancer properties inC. nutansleaf extract. Reductions in cell viability (0–78%) and proliferation (2–77%), as well as a synergistic anticancer effect, were identified in TNBC cells when treated with a combination of cisplatin andC. nutans. Furthermore, apoptotic induction via increased caspase-3/7 activity (MDA-MB-231: 2.73-fold; MDA-MB-468: 3.53-fold), and a reduction in cell invasion capacity to 36%, were detected in TNBC cells when compared to single cisplatin andC. nutanstreatments. At the mRNA level, cisplatin andC. nutansdifferentially regulated specific genes that are responsible for proliferation and differentiation.ConclusionOur findings demonstrate that the combination of cisplatin andC. nutansrepresents a potential treatment for TNBC.