Arteriovenous malformations (AVM) are abnormal arteriovenous shunt lesions that predominantly occur in the brain or spinal cord. However, obstructive hydrocephalus resulting from an unruptured AVM occurs rarely. Herein, we report the case of a patient with obstructive hydrocephalus caused by an unruptured cerebellar AVM that was treated with an endoscopic third ventriculostomy (ETV), and further, we present a literature review. An 11-year-old girl presented to our department with headache, nausea, and vomiting. Magnetic resonance imaging and angiography revealed a cerebellar AVM. Additionally, we used the findings of digital subtraction angiography and confirmed a Spetzler–Martin grade 5 cerebellar AVM fed by branches of the bilateral posterior cerebral and bilateral anterior and posterior cerebellar arteries. We initiated conservative therapy; however, 10 years after her initial presentation, the patient’s acute obstructive hydrocephalus due to aqueductal occlusion had worsened. Therefore, we performed an endoscopic third ventriculostomy that resolved the hydrocephalus and improved the patient’s clinical condition. In our review of the literature, we observed that, in most cases, hydrocephalus resulted from deep-seated AVM; furthermore, ETV effectively resolved the hydrocephalus. To summarize, ETV can be an effective alternative to emergent ventriculoperitoneal shunting to treat acute obstructive hydrocephalus caused by unruptured intracranial AVM.