Characterized by rapid proliferation and therapeutic resistance, glioblastoma (GBM) represents the deadliest primary CNS neoplasm, demonstrating a low survival rate and high mortality rate in patients. This is mainly related to the development of GBM more specifically due to the abnormal metabolism within cells. SHMT2 (serine hydroxymethyltransferase 2) acts as a pivotal metabolic regulator in neoplastic cells, driving one-carbon unit transfer essential for nucleotide biosynthesis. Here, we explored the mechanism of SHMT2 mediated GBM occurrence. In this study, SHMT2 expression was assessed in GBM cells and tissues. In vitro experiments were performed to investigate the functional role of SHMT2. The detailed mechanisms of SHMT2-mediated cell metabolism were addressed. Xenograft model analysis explored the influence of SHMT2 on GBM development. The expression level of SHMT2 in GBM clinical tissues and cell lines is higher than that in normal tissues. The downregulation of SHMT2 inhibits the proliferation ability and metabolic process of GBM cell lines. Mechanism dissection revealed that SHMT2 enhanced phosphatase and tensin homolog (PTEN) N6-methyladenosine (m6A) modification through the endogenous methyl donor SAM mediated by SHMT2 via serine/glycine one carbon metabolic networks. In addition, Xenograft model analysis showed that knockdown of SHMT2 inhibited the development of GBM tumors. SHMT2 promotes the tumorigenesis of glioblastoma by regulating the m6A modification of PTEN.