Background Subclavian aneurysms are rare in clinic; right subclavian artery aneurysms (SAAs) are more common than left SAAs in clinical practice. Although the causes and methods of treating subclavian aneurysms have been studied, it is still unknown how they form naturally. Objective While describing the uncommon subclavian aneurysm, examine the pertinent literature to discuss its etiology and treatment outcomes, and offer some recommendations for this patient’s treatment plan. Methods In this case report, we describe a man patient who had a right subclavian proximal aneurysm that was discovered by accident. No clear clinical symptoms or signs were present in the patient. Upon admittance, an examination revealed an aneurysm in the vertebral artery but no peripheral embolization or compression symptoms. The patient refused operation, so we opted for follow-up instead. Result The patient took an ultrasound examination at our first follow-up appointment 3 months after discharge, and the results showed no thrombosis or appreciable aneurysm enlargement. Follow-up appointments for 6 months and a year have begun. Conclusion Follow-up is a good method to monitor the course of subclavian aneurysms without a clear indication for surgery when there is a clear operation mode and risk.