The efficacy of primary sutureless repair for supracardiac total anomalous pulmonary venous connection (TAPVC) needs to be confirmed. This study aimed to compare the long-term outcomes between the conventional surgery and the sutureless technique with a modified approach in superior TAPVC. Between January 2008 and December 2018, 173 patients with supracardiac TAPVC underwent surgery either with the conventional procedure (n = 130) or the sutureless repair (n = 43). Multivariate analysis and competing-risk analysis were used to identify risk factors for early death and postoperative pulmonary venous obstruction (PVO), respectively. Among 173 patients who underwent repair of supracardiac TAPVC, 46 (28%) had preoperative PVO, and 22 (12.7%) had postoperative PVO. The sutureless group had a lower postoperative PVO rate compared with the conventional group (p = 0.027). The risk factors for death were age ≤ 28 days [odds ratio (OR), 11.56; 95% confidence interval (CI) 1.33–100.47, p = 0.015], weight ≤ 3 kg (OR 9.57; 95% CI 1.58–58.09, p = 0.009), emergency operation (OR 19.24; 95% CI 3.18–116.35, p = 0.002), cardiopulmonary bypass time (OR 2.16; 95% CI 1.36–3.43, p = 0.003), cross-clamp time (OR 1.73; 95% CI 1.20–2.50, p = 0.022), and duration of ventilation (OR 1.11; 95% CI 1.02–1.21, p = 0.027). Age ≤ 28 days [Hazard Ratio (HR) 1.92; 95% CI 1.92–11.02, p < 0.001] and preoperative PVO (HR 41.70; 95% CI 8.15–213.5, p < 0.001) were associated with postoperative PVO. The sutureless repair is a reliable technique for supracardiac TAPVC. Age ≤ 28 days is associated with 30-day mortality and postoperative PVO.