Notch1 was validated as the direct target gene of miR-3178, which was confirmed by the dual-luciferase reporter assay. miR-3178 decreased the expression of Notch1 and restoration of Notch1 expression attenuated the inhibitory effects of miR-3178 on cell proliferation, metastasis, and the EMT in TNBC. miR-3178 inhibited cell proliferation and metastasis by targeting Notch1 in TNBC, and the restoration of miR-3178 might be a potential therapeutic strategy for TNBC.