Purpose <p>Gliomas are aggressive tumors with poor treatment outcomes. Tasimelteon, an FDA-approved melatonin receptor agonist with favorable blood-brain barrier penetration, has unexplored anti-tumor potential. This study investigated whether Tasimelteon inhibits glioma proliferation through ferroptosis induction.</p> Methods <p>Cell viability, colony formation, and immunofluorescence were employed to assess the effects of Tasimelteon on glioma cells. Ferroptosis was assessed by measuring lipid peroxidation markers (MDA, 4-HNE, BODIPY 581/591 C11) and ROS levels, and mitochondrial damage was detected by TEM. Mechanisms were examined through Western blotting, qPCR, dual-luciferase reporter assays, site-directed mutagenesis and molecular docking. In vivo, LN229-Luc glioma cells were orthotopically injected into mouse brains, followed by Tasimelteon treatment. Tumor growth was monitored by bioluminescence imaging, and body weight and survival were recorded. Systemic toxicity was evaluated through H&amp;E staining of major organs.</p> Results <p>Tasimelteon decreased glioma cell viability and colony formation in dose- and time-dependent manners. Mechanistically, Tasimelteon induced ferroptosis, characterized by elevated lipid peroxidation markers (MDA, 4-HNE) and ROS levels, along with mitochondrial damage observed by TEM. This process was accompanied by ACSL4 upregulation. Further investigation revealed that Tasimelteon bound to SP1 at Gln465 and Leu467 residues, stabilizing the protein and enhancing ACSL4 transcription, independent of MT1/MT2 receptor activation. In orthotopic glioma models, Tasimelteon suppressed tumor growth by inducing ferroptosis and prolonged survival without systemic toxicity.</p> Conclusion <p>Tasimelteon inhibits glioma growth by inducing ferroptosis via the SP1/ACSL4 pathway, offering a novel therapeutic approach.</p>