Data are limited on outcomes associated with mitral valve surgery in infants. Prior studies report high mortality and increased risk for late cardiac failure particularly for those with mitral stenosis. We sought to evaluate outcomes in patients with mitral stenosis (MS) or regurgitation (MR) who had mitral valvuloplasty or replacement in the first year of life. A retrospective analysis of all patients in a single institution who underwent mitral valvuloplasty or replacement in their first year of life from 2004 to 2016 (n = 25), excluding patients with single ventricle pathology or those undergoing surgery for atrioventricular canal defect, was carried out. Median age and weight at surgery were 76.5 days (range 2–329) and 4.5 kg (range 3.0–10.1), respectively. The primary mitral pathology was MR in 16 and MS in 9 patients. Median follow-up among living patients was 4 years (range 106 days–12.3 years). Overall survival was 96% at 30 days and 87.8% at 1, 5, and 10 years. There were three early deaths (12%), all within 6 weeks of surgery. There were no late deaths. Three patients required valve replacement, 1 of which had a primary mitral valve replacement and died within 30 days of surgery. Re-intervention-free survival (surgical and catheter based) was 83.8%, 73.3%, and 48.9% at 1, 5, and 10 years per Kaplan–Meier estimates. There was no difference in re-intervention-free survival between patients with MR versus MS. No risk factors for death or re-intervention were identified. Mitral valvuloplasty and replacement can be performed in infants under 1 year of age with acceptable survival and need for re-intervention.