Intraosseous arteriovenous malformation (AVM) in the craniofacial region is rare. When it occurs, it is predominantly located in the mandible and maxilla. We encountered a 43-year-old woman with Klippel-Trenaunay syndrome affecting the right lower extremity who presented with a left orbital chemosis and proptosis mimicking the cavernous sinus dural arteriovenous fistula. Computed tomography angiography revealed an intraosseous AVM of the sphenoid bone. The patient's symptoms were completely relieved after embolization with Onyx. We report an extremely rare case of intraosseous AVM involving the sphenoid bone, associated with Klippel-Trenaunay syndrome.