BACKGROUND Kawasaki disease (KD), a systemic vasculitis, affects children aged <5 years and is the leading acquired cardiovascular disease in developed countries. Although intravenous immunoglobulin is an effective treatment for KD and decreases the rate of cardiovascular complications, some patients still develop coronary sequelae, including coronary aneurysms and myocardial infarction. CASE REPORT A 9-year-old boy was diagnosed with KD at the age of 6 years. For coronary sequelae of a giant coronary artery aneurysm (CAA) 8.8 mm in diameter, he was prescribed aspirin and warfarin. At 9 years old, he visited the Emergency Department because of acute chest pain. Electrocardiography revealed an incomplete right bundle branch block and ST-T change over right and inferior leads. Also, troponin I was elevated. Coronary angiography found acute thrombotic occlusion of the right CAA. We performed aspiration thrombectomy with intravenous tirofiban. Coronary angiography and optical coherence tomography (OCT) images later found white thrombi, calcification, destruction of media layer, irregular intimal thickening, and uneven intima edge. We prescribed antiplatelet therapy and warfarin, and he was doing well at a 3-year follow-up. CONCLUSIONS OCT is a promising modality that can impact the clinical care in patients with coronary artery disease. This report presents treatment management and OCT images of KD complicated with a giant CAA and acute myocardial infarction. We used aspiration thrombectomy in combination with medical treatments as the initial intervention strategy. Afterward, the OCT images showed vascular wall abnormalities, which were helpful for defining the future risk and decision making of further coronary interventions and medical treatments.