Non-small cell lung cancer (NSCLC) is a predominant form of lung cancer that is often diagnosed at an advanced metastatic stage. The processes of cancer cell migration and invasion involve epithelial-to-mesenchymal transition (EMT), which is crucial for metastasis. Targeting cancer aggressiveness with effective plant compounds has gained attention as a potential adjuvant therapy. Eurycomanone (ECN), a bioactive quassinoid found in the root of Jack, has demonstrated anti-cancer activity against various carcinoma cell lines, including human NSCLC cells. This study aimed to investigate the in vitro effects of ECN on the migration and invasion of human NSCLC cells and to elucidate the mechanisms by which ECN modulates the EMT in these cells. Non-toxic doses (≤IC20) of ECN were determined using the MTT assay on two human NSCLC cell lines: A549 and Calu-1. The results from wound healing and transwell migration assays indicated that ECN significantly suppressed the migration of both TGF-β1-induced A549 and Calu-1 cells. ECN exhibited a strong anti-invasive effect, as its non-toxic doses significantly suppressed the TGF-β1-induced invasion of NSCLC cells through Matrigel and decreased the secretion of MMP-2 from these cancer cells. Furthermore, ECN could affect the TGF-β1-induced EMT process in various ways in NSCLC cells. In TGF-β1-induced A549 cells, ECN significantly restored the expression of E-cadherin by inhibiting the Akt signaling pathway. Conversely, in Calu-1, ECN reduced the aggressive phenotype by decreasing the expression of the mesenchymal protein N-cadherin and inhibiting the TGF-β1/Smad pathway. In conclusion, this study demonstrated the anti-invasive activity of eurycomanone from Jack in human NSCLC cells and provided insights into its mechanism of action by suppressing the effects of TGF-β1 signaling on the EMT program. These findings offer scientific evidence to support the potential of ECN as an alternative therapy for metastatic NSCLC.