We describe a case of a 52-year-old female with Turner syndrome found to have an isolated 3.5-cm left subclavian artery aneurysm. Surgical intervention was performed to decrease the risk of compressive symptoms, distal embolization, and rupture. This entailed exclusion of the aneurysm proximally using thoracic stent graft, carotid-subclavian bypass, and ligation of the subclavian artery distal to the aneurysm. One-year follow-up demonstrated exclusion of the aneurysm with a 5-mm reduction in maximum aneurysm sac diameter. This case represents the management of a rare isolated left subclavian artery aneurysm, in the setting of Turner syndrome, treated with a successful endovascular approach.