Objective Moyamoya vasculopathy associated with skull base tumors has been rarely reported except for partially removed pituitary adenoma and craniopharyngioma. Only a single case of meningioma resulted in vast cerebral infarction. Surgical treatment carries a high risk of damage to the compensatory collateral circulation through leptomeningeal anastomosis leading to a devastating outcome. Case presentation A 46-year-old woman presented to our hospital with progressive visual disturbance. She had a history of medically treated moyamoya vasculopathy. Head magnetic resonance imaging revealed a well-demarcated skull base tumor extending from the planum sphenoidale to the diaphragm sellae. The patient had no cerebral ischemic symptoms, but iodine-123 N-isopropyl-p-iodoamphetamine single-photon emission computed tomography indicated bilateral hemodynamic compromise. Modified extended transsphenoidal surgery was performed, resulting in successful removal without complications including cerebral ischemia. Conclusion The very low tolerance to cerebral ischemia associated with moyamoya disease manipulation in this location carries an extremely high risk of cerebral infarction. This is the first report of a basal meningioma associated with moyamoya syndrome that was successfully removed. The modified extended transsphenoidal approach is the first-line surgery for skull base meningioma located in the para-midline region.