Kawasaki disease (KD) is an acute systemic vasculitis of unknown etiology that affects children. There are few reports that describe the Epstein-Barr virus (EBV) as the possible infectious agent of KD. Here, we describe a case of KD in a 15-year-old boy complicated with giant coronary artery aneurysms, pericardial effusion, and splenic infarction. The clinical course of KD was refractory to intravenous gamma globulin and aspirin. Our patient also showed typical findings of concomitant EBV-associated infectious mononucleosis, such as hepatosplenomegaly and generalized lymphadenopathy, with EBV-positive atypical lymphoid hyperplasia. He improved dramatically after receiving intravenous methylprednisolone followed by oral prednisolone. Ultimately, the coronary artery aneurysms remained as the only sequelae. We report a rare case of adolescent KD with EBV-associated infectious mononucleosis and splenic infarction.