BACKGROUND: A 49-year-old woman with a history of hypertension presented to the emergency department with right eye redness, proptosis, orbital fullness, and blurry vision. She had initially been diagnosed with an orbital pseudotumor, and the symptoms worsened over a course of steroids. Computed tomography angiography raised concern for a carotid-cavernous fistula (CCF), which was subsequently confirmed by digital subtraction angiography. OBSERVATIONS: She underwent fistula coil embolization via the internal maxillary artery and inferior ophthalmic vein (IOV). At the 2-month follow-up, she reported complete resolution of diplopia, orbital fullness, and proptosis. An ophthalmology examination revealed normal visual fields bilaterally. LESSONS: CCF embolization is rarely performed through the IOV, with only 5 reported cases in the literature. This case demonstrates that the procedure can be easily performed if the anatomy is favorable over the superior ophthalmic vein, with the illustration of good cosmetic outcomes. https://thejns.org/doi/10.3171/CASE24183.