An 1186-g infant was born at 27 weeks' gestation. Echocardiography showed critical aortic stenosis, a dilated left ventricle (left ventricular end-diastolic diameter, 16.9 mm), and poor left ventricular function (left ventricular ejection fraction, 8.5%). Due to duct-dependent systemic circulation, the patient underwent a hybrid intervention consisting of bilateral pulmonary artery banding (PAB) and balloon aortic valvuloplasty (BAV) via the ascending aorta on day 2. A stainless steel tip and a 6-French introducer were combined to create an access device. The access device was inserted into the ascending aorta, through which balloon catheters were manipulated. On day 4, echocardiography showed a left ventricular ejection fraction of 48% and dominant antegrade blood flow in the aortic arch. The pulmonary artery bands were removed and the ductus was clipped on day 8 to establish in-line circulation. After re-balloon aortic valvuloplasty for restenosis, the patient was discharged from the hospital at 7 months of age. The clinical implications of this case are: the ascending aortic approach is feasible for BAV in low-birth-weight neonates; and bilateral PAB performed concomitantly with BAV may be efficient for neonates with critical aortic stenosis and poor left ventricular function.