Congenital heart defects are the most common singular congenital organ malformation. Due to advances in medical care, more than 95% of affected persons now reach adulthood. However, congenital heart defects are often associated with residuals or sequelae that require lifelong specialized care. Lack of or irregular follow-up care leads to worse outcomes. Nevertheless, follow-up care for adults with congenital heart disease (ACHD) is still often inconsistent in reality, and many patients receive care outside of qualified structures.The transition process-the shift from pediatric to adult medical care-is critical. Many affected individuals experience little to no subjective limitations at this stage. Nevertheless, they must gradually take responsibility for their health while adapting to an unfamiliar healthcare provider.A structured transition process aims to improve continuity of care, promote disease acceptance, and prevent gaps in medical care. Both, patients and their primary care providers must be well-informed and aware of specialized care structures. Interdisciplinary collaboration among primary care providers, pediatric and ACHD specialists, and adult cardiologists is essential and should be supported by transition programs or patient organizations.Failure in the transition process primarily puts at risk the health of affected individuals but can also unnecessarily strain the healthcare system. A successful transition and a comprehensive, specialized care network are key to sustainably improving the prognosis of ACHD patients.