High-grade meningiomas make up a relatively minor proportion of meningiomas, which are one of the most common types of primary intracranial tumors in adults. Though rare, a considerable portion of high-grade meningiomas arise from malignant transformation of benign meningiomas. The 2021 World Health Organization (WHO) classification criteria introduced molecular markers in the diagnosis and grading of central nervous system (CNS) tumors and assigned certain genomic mutations to grade 3 meningiomas. We report a case of a 54-year-old male patient who underwent stepwise malignant transformation of meningioma from WHO grade 1 to grade 3 within 10 years, during the course of five surgeries followed by adjuvant stereotactic radiosurgery and radiotherapy. We performed next-generation sequencing (NGS) on the most recent grade 3 meningioma specimen and found that it carried a telomerase reverse transcriptase promoter (p) mutation (c.-124C>T) in accordance with the 2021 WHO criteria for grade 3 meningiomas. We then retrospectively examined the previous grade 1 and 2 specimens and found them to have the same mutation. We reviewed the significance of molecular markers in the diagnosis of meningiomas, possible genetic alterations associated with their malignant transformation, and what measures could be taken to effectively manage meningiomas considering NGS findings.