Abstract: Background and Objective: Malignant gliomas, particularly Glioblastoma (GBM) are a primary cause of mortality and morbidity in brain malignancy. The p38 MAPK signalling reduction leads to the tumorigenesis of GBM. Recognizing novel agents that can regulate p38 MAPK signalling is essential for GBM treatment. Goniothalamin (GTN), a naturally arising styryl-lactone compound with accepted anticancer properties. To explore the anticancer and apoptosis efficacy of GTN on GBM human cancer cells. Materials and Methods: The U251 malignant cells were treated with various GTN dosages to fix its molecular action on cells viability, apoptosis, cell cycle regulation and p38 MAPK/JNK/ERK protein expressions. The anti-proliferative activity of GTN on U-251 cells has been exposed by CCK-8 assay and live/dead assay. Results: Apoptotic death contributed by GTN on the reduction of U251 cell viability was demonstrated by DAPI staining, Bax and Bcl-2 protein expressions. The G2/M cell cycle regulation was also confirmed by reducing the protein expression of cyclin B1, CDK1 and enhanced p21 level. Additionally, GTN induced apoptosis via p-p38 upregulation and little effect on p-JNK1 and p-ERK1 levels. Conclusion: In this study, GTN treatment induces proapoptotic factors and inhibits proliferative markers by inhibiting p38 MAPK expression in glioblastoma cells. Our findings recommend that GTN would be beneficial for GBM treatment.