Scalp arteriovenous fistulas (AVFs) are rare vascular anomalies characterized by abnormal connections between arterial and venous systems in the scalp. These lesions can lead to significant complications, including chronic headaches, tinnitus, cosmetic deformities, and in severe cases, high-output cardiac failure or intracranial hemorrhage. We present a case of a middle-aged female patient with a 20-year history of a pulsating mass on the left parietal scalp. Magnetic resonance imaging and cerebral angiography confirmed the presence of a scalp AVF with multiple arterial feeders from the external carotid artery and venous drainage into the left external jugular vein. Due to the tortuosity of the feeding arteries, a transarterial approach was unsuccessful, leading to the decision to perform transvenous embolization with balloon occlusion using Onyx-18. The procedure resulted in complete obliteration of the AVF without complications. This case highlights the efficacy of transvenous embolization with balloon occlusion as a treatment option for complex scalp AVFs, particularly when transarterial access is challenging.