Background: Extracorporeal membrane oxygenation (ECMO) provides life-saving support but carries considerable risks, particularly in neonates and postcardiotomy patients. The vasoactive inotropic score (VIS), which measures cardiovascular support, shows potential as a prognostic marker; however, its role in ECMO remains underexplored. This study aims to assess the impact of vasoactive inotropic score values on mortality and ECMO-related complications in patients undergoing ECMO due to cardiopulmonary failure. Methods: We analyzed 106 pediatric patients who underwent ECMO between January 2011 and January 2021. The demographics, ECMO indications, cannulation strategies, VIS at initiation, complications, and outcomes were reviewed. The primary endpoint was in-hospital mortality. ROC curve analysis and multivariate logistic regression evaluated the prognostic utility of VIS and ECMO-related complications. Results: The in-hospital mortality rate was 57.5%, which was higher among neonates (78.6%), infants (62.0%), and patients who underwent central VA ECMO. VIS at cannulation was independently associated with mortality in multivariate analysis (median VIS: 28 in non-survivors vs. 20 in survivors; p<0.001). A VIS value >=28 demonstrated strong predictive ability for mortality (area under the curve: 0.815; sensitivity: 82%, specificity: 78%). ECMO-related complications occurred in 62.3% of patients, with renal complications requiring dialysis emerging as the strongest mortality predictor (odds ratio [OR]: 3.40; p<0.001), followed by neurological complications (OR: 2.01; p=0.027). Conclusion: A VIS score >=28 at ECMO initiation strongly predicted in-hospital mortality. Renal complications substantially worsen clinical outcomes. Incorporating VIS into risk stratification protocols and implementing strategies to prevent major complications may improve prognosis of pediatric patients on ECMO.