Takayasu arteritis is a chronic inflammatory disease of unknown etiology primarily affecting the aorta and its major branches and usually occurring in the second or third decade of life. Here, we report a case of Takayasu arteritis in a 10-month-old patient. The infant presented with signs of congestive heart failure and severe aortic regurgitation. Echocardiography and computed tomography angiography showed an abnormally dilated thoracic and abdominal aorta. The infant was initially treated with prednisolone, followed by commissuroplasty of the aortic valve but neither approach ameliorated the heart failure. The patient was eventually treated with a mechanical aortic valve replacement surgery at the age of 12 months, and her condition stabilized. Although unusual, this case indicates that the diagnosis of Takayasu arteritis should be considered in children with unexplained systemic symptoms, aortic valve regurgitation, and heart failure. Because severe aortic regurgitation may be a fatal complication of Takayasu arteritis, early aortic valve replacement surgery should be considered, even in very young children.