Glioblastoma multiforme (GBM) is a highly malignant central nervous system tumor with a poor prognosis. Developing new therapeutic drugs is crucial. This study evaluates deoxyelephantopin (DET), a major component of *Elephantopus scaber* L., for its potential anti-GBM effects. The effects of DET on GBM cell lines were investigated using the MTT assay and Annexin-V kit to assess cell death and apoptosis. Western blot analysis examined apoptosis and cell cycle-related proteins. ELISA kits measured VEGF and TGF-β levels. In vivo, NOD SCID mice were injected with GL-261 cells and treated with DET to evaluate tumor growth and survival. DET inhibited GBM cell growth in a time- and dose-dependent manner. MTT and Annexin-V assays confirmed cell death and apoptosis. Western blot analysis showed DET downregulated Bcl-2 and increased caspase-3, Bax, and cytochrome c levels. ELISA results indicated that DET suppressed VEGF and TGF-β expression. DET treatment also decreased phosphorylation of AKT and STAT-3, CDK4, cyclin D2, MMP2, and MMP9 levels. In vivo, DET significantly inhibited tumor growth and improved survival rates in mice. DET exhibits significant in vitro and in vivo anticancer effects, making it a promising candidate for further research and potential clinical application against GBM.