The optimal strategy for treating tandem lesions with obstruction that is distal and proximal to the ipsilateral vasculature is controversial. We report a case of acute ischemic stroke (AIS) in a 60‒year‒old man who was admitted to our hospital with tandem lesions. Upon his arrival, we observed right‒sided paresis and motor aphasia. His score on the National Institutes of Health Stroke Scale (NIHSS) was 8. An acute cerebral infarction had been caused by occlusion of the M2 segment of the left middle cerebral artery and by an ipsilateral occlusion of the internal carotid arteries. We diagnosed the infarction as tandem lesions. Cerebral angiography was performed, and thrombolytic therapy was given, and the patient’s neurological deficit disappeared the day. Antiplatelet drug therapy was then started. The patient’s medical history included ipsilateral oropharyngeal cancer radiotherapy, and his left internal carotid artery severe stenosis was thought to be a result of this treatment. On the fourth day after the patient’s AIS onset, consciousness disorder, right‒sided complete paralysis, and global aphasia suddenly appeared. Emergency MRI revealed occlusion of the M1 segment of the left middle cerebral artery. The patient’s NIHSS score was 17. Endovascular treatment was selected because the patient could not undergo thrombolytic therapy. First, the occluded blood vessel was expanded to a minimum width; a device was passed through to reopen the proximal occluded blood vessel. After reperfusion of the M1‒2 segment with a mechanical thrombectomy, a stent was placed in the internal carotid artery with a distal protection device, and good patency was obtained. Postoperatively, signal changes were observed in the basal ganglia on diffusion‒weighted imaging, but the neurological symptoms were improved (Modified Rankin Scale score, 1), except for motor aphasia and mild neurological dysfunction. On day 26 after AIS onset, the patient was discharged from our hospital for further rehabilitation. The use of the combination of a mechanical thrombectomy and carotid artery stenting was an effective strategy for this patient’s tandem lesions that were caused by the artery‒to‒artery embolism from arteriosclerotic carotid artery stenosis and the resultant cerebral infarction.