Chryseobacterium meningosepticum is an uncommon pathogen causing adult bacterial meningitis. Herein, we report the case history of one 21-year-old woman with this uncommon central nervous system infection. A diagnosis of adult C. meningosepticum meningitis can only be confirmed by a positive cerebrospinal fluid (CSF) culture. The patient had insulin-dependent diabetes mellitus as the underlying condition associated with this infection. The clinical presentations were fever, headache, consciousness disturbance, and seizure. CSF analysis revealed a purulent inflammatory reaction. After a 21-day course of intravenous cefepime (6 g/day) treatment, this patient was discharged in a state of complete recovery.