RAB1A acts as an oncogene in various cancers, and emerging evidence has verified that RAB1A is an mTORC1 activator in hepatocellular and colorectal cancer, but the role of RAB1A in breast cancer remains unclear. In this investigation, RAB1A siRNA was successfully transfected in MDA-MB-231 and BT-549 human triple-negative breast cancer cells, and verified by real‑time quantitative polymerase chain reaction and western blotting. Then, MTT cell proliferation, colony formation, cell invasion and wound healing assays were performed to characterize the function of RAB1A in the breast cancer cell lines. Downregulation of RAB1A inhibited cellular growth, cell migration, cell invasion and cell epithelial-mesenchymal transition. Furthermore, compared with NC siRNA transfected cells, RAB1A siRNA transfected breast cancer cells inhibited the phosphorylation of S6K1, the effector molecular of mTORC1. Collectively, our data suggested that RAB1A acts as an oncogene by regulating cellular proliferation, growth, invasion and metastasis via activation of mTORC1 pathway in triple-negative breast cancer.