Atrial fibrillation is the most common cardiac arrhythmia, and electrical cardioversion for atrial fibrillation contributes to the formation of systemic thromboembolism. In particular, the increase in the occurrence of thromboembolic events is associated with postcardioversion atrial and atrial appendage "stunning". Most thromboembolic events after cardioversion were found in the cerebral artery. In this case, the patient had a thromboembolism in the brachial artery region, which has not been reported in literature reviews. We describe the first case of brachial arterial thromboembolism which occurred 3 days after cardioversion of atrial fibrillation, and was completely resolved by thrombolytic therapy.