Unicuspid aortic valve (UAV) is a rare congenital cardiac anomaly. There are two forms of UAV, including unicuspid acommissural and unicuspid unicommissural. Definitive management for UAV is surgical intervention, but due to the rarity of UAV, the long-term surgical outcomes as well as overall prognosis are not known. Here, we present the case of a 19-year-old patient who was found to have a UAV prenatally and underwent a mechanical aortic valve replacement through an upper hemi-sternotomy due to elevated aortic stenosis gradients and presence of symptoms.