As survival among patients with congenital heart disease (CHD) continues to improve, the population of adults with CHD (ACHD) is rapidly growing. These patients often present with complex anatomy, prior surgical repairs, residual hemodynamic lesions, and progressive physiologic derangements that require lifelong surveillance and specialized care. When circulatory or respiratory failure occurs, extracorporeal membrane oxygenation (ECMO) may be lifesaving; however, its use in ACHD poses unique challenges. Indications for ECMO, particularly veno-arterial (VA) support, include refractory cardiogenic shock, cardiac arrest, and postoperative low-cardiac output syndrome, while veno-venous (VV) ECMO may be indicated in select ACHD patients with respiratory failure. Complex circulations such as Fontan physiology, systemic right ventricles after atrial switch operations, and cyanotic heart disease require careful individualized planning, particularly for cannulation strategies and perfusion goals. Anatomic variations, prior surgeries, vascular access issues, and special considerations such as right-to-left shunts complicate ECMO initiation and management. Despite high reported mortality – especially in patients with Fontan circulation – ECMO can provide an effective bridge to recovery or transplant in carefully selected patients. Given the unique risks and resource demands, ACHD patients requiring ECMO support should ideally be managed in specialized centers with multidisciplinary expertise. This review outlines the anatomical and physiological considerations, indications, cannulation strategies, and outcomes associated with ECMO in the ACHD population, providing a framework for decision-making in this increasingly relevant clinical scenario.