Accumulating evidence indicates that mitotic checkpoint serine/threonine kinase B (BUB1B) plays a critical role in multiple types of cancer. However, the biological function and molecular regulatory mechanism of BUB1B in glioblastoma (GBM) remain unclear. In the present study, we identified that BUB1B expression was enriched in GBM tumors and was functionally required for tumor proliferation both in vitro and in vivo. Clinically, BUB1B expression was associated with poor prognosis in GBM patients and BUB1B‑dependent radioresistance in GBM was decreased by targeting BUB1B via shRNAs. Mechanistically, forkhead box protein M1 (FOXM1) transcriptionally regulated BUB1B expression by binding to and then activating the BUB1B promoter. Therapeutically, we found that FOXM1 inhibitor attenuated tumorigenesis and radioresistance of GBM both in vitro and in vivo. Altogether, BUB1B promotes tumor proliferation and induces radioresistance in GBM, indicating that BUB1B could be a potential therapeutic target for GBM.