Background: Turcot syndrome (TS) is an extremely rare genetic disorder characterized by the concurrent occurrence of primary brain tumors and colorectal cancer. The prognosis for patients with TS is typically poor. Case presentation: A 57-year-old man with TS who developed recurrent glioblastoma and had a family history of colon cancer is reported. In 2022, the patient underwent robot-assisted stereotactic surgery for the resection of a central nervous system (CNS) tumor. Molecular genetic analysis identified microsatellite instability in the DNA mismatch repair (MMR) gene, confirming the diagnosis of TS. Additional mutations in the ATM and TP53 genes were also detected, which are rarely associated with TS. Despite treatment with the Stupp regimen, the patient experienced acute neurological deterioration, ultimately resulting in death 15 months after the onset of symptoms. Conclusion: Molecular diagnostics play a crucial role in guiding appropriate care and management for patients with TS. Early diagnosis, genetic testing, and preventive measures are essential for the effective management of this condition.