Background: Overexpression of transforming growth factor-β (TGF-β) and its cancer regulators are the major phenomena in oral cancer. The study aimed to investigate the anticancer effect of degalactotigonin (DGT), a steroidal glycoside from Solanum nigrum on oral cancer. Objectives: The study aimed to investigate the anti-invasion and apoptotic induction effect of DGT in oral squamous cell carcinoma (OSCC) cells through inhibiting non-canonical TGF-β signalling. Materials and Methods: Human oral cancer KB (KERATIN-forming tumor cell line HeLa) cells were chosen to study the anti-cancer activity of DGT in vitro experiments. The cytotoxic effect of DGT was evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay. Cell growth, DNA damage, invasion inhibition and apoptosis activation were evaluated by mitochondrial membrane potential (ΔΨM), comet assay, reactive oxygen species (ROS) and AO/EtBr staining. The DGT effect on protein expression levels related to invasion, apoptotic markers and its activation signalling pathways on KB cells were examined by western blotting. Results: We found that DGT antioxidant properties reduced cell viability, generates ROS, enhanced DNA damage, and MMP dissipation. Further, TGF-β inhibitions resulted in a reduction of extracellular signal-regulated kinase (ERK), NF-κB and activation of JNK, p38 which increase ROS in a cancer cell that downregulates cyclin-D1, PCNA, MMP-2, MMP-9, Bcl-2 and increases Bax, Caspase-9, Caspase-3 protein expressions that simultaneously subdues the cancer developments. Conclusion: These findings suggest that DGT inhibiting TGF-β mediated ERK, NF-κB and activation of JNK, p38 caused tumour cell death via ROS stimulation and apoptosis.