Aims: Fontan completion is traditionally performed in early childhood; however, in regions with delayed diagnosis or limited resources, some patients undergo Fontan surgery at older ages. This study aimed to evaluate perioperative and early-to-midterm outcomes of Fontan completion performed at the age of 7 years or older in a single-center cohort.Methods: This retrospective study included 26 patients who underwent Fontan completion at ≥7 years of age between 2020 and 2025. Preoperative demographic, echocardiographic, catheterization, operative, and postoperative data were reviewed. All patients underwent extracardiac Fontan procedures. Fenestration was performed selectively based on pulmonary artery pressure and intraoperative findings. Descriptive statistical analyses were conducted.Results: The mean age at Fontan completion was 12.6±6.1 years (median, 10.5 years), and the mean body weight was 28.8±16.0 kg. The most common underlying diagnoses were double-inlet left ventricle (23.1%) and tricuspid atresia (19.2%). The mean preoperative pulmonary artery pressure was 12.6±2.9 mmHg. Fenestration was performed in 4 patients (15.3%). Early postoperative complications included diaphragmatic paralysis in 11.5%, pulmonary infection in 15.3%, and prolonged pleural drainage in 11.5% of patients. One patient (3.8%) required postoperative extracorporeal membrane oxygenation due to low cardiac output syndrome and could not be weaned. No new permanent arrhythmias were observed in the early postoperative period.Conclusion: Fontan completion beyond 7 years of age can be performed with acceptable early outcomes in carefully selected patients with favorable hemodynamic profiles. Age alone should not be considered an absolute contraindication; instead, individualized assessment focusing on pulmonary artery pressure, ventricular function, and atrioventricular valve competence is essential. Selective fenestration and appropriate surgical strategies may help reduce early morbidity in delayed Fontan candidates.