Tetrahydrocurcumin (THC), the major metabolite of turmeric, is an anti-inflammatory and antioxidant. Although it has been demonstrated that THC inhibits the growth of various other types of cancer cells, its effects on glioma cells have not yet been studied. We intended to understand the mechanisms by which THC influences the proliferation and death of glioma cells. Several concentrations of THC were employed to treat U87MG cells. The CCK8 assay assessed cell proliferation and wound healing, whereas the Transwell assay assessed cell migration and invasion. The percentage of cells in the apoptotic state and those still in the cell cycle were measured using flow cytometry and Western blotting under different treatment conditions. The Western blotting and immunofluorescence assays were used to examine the protein expression levels before and after the PI3K/Akt/mTOR pathway was altered. In a dose-dependent manner, THC decreased glioma cell proliferation, migration, and invasion. Cell cycle arrest and apoptosis were detected in THC-treated glioma cells using flow cytometry and western blotting. Immunofluorescence and western blotting analysis showed that THC inhibits the PI3K/Akt/mTOR signalling pathway, which is responsible for its anti-glioma action. Furthermore, the effects of THC on glioma cell survival, apoptosis, and cell cycle block were abolished in the presence of the PI3K activator 740Y-P. THC has been shown to have anti-glioma cell properties through its impact on the PI3K/Akt/mTOR signalling pathway, suggesting it may be effective as a glioma treatment.