Congenital heart disease is one of the most common congenital defects with a high mortality and morbidity rate. Children with congenital heart disease step from pediatric care to adult care during adolescence. This situation has brought up transitional care, which is defined as the purposeful and planned movement of adolescents and young adults with chronic physical and medical conditions from pediatric to adult-oriented health systems. Since adolescents with congenital heart disease are at high risk for complications in adulthood, it is very important to raise awareness, increase the level of readiness for adult care and gain self-management skills during the transition phase. This study was planned as a randomized controlled experimental study to evaluate the effect of the developmental transition care model applied to adolescents with congenital heart disease during the transition from pediatric care to adult care on the transition readiness level, self-management skills and care satisfaction of adolescents. Studies have shown that both adolescents with congenital heart disease and their caregivers need professional support, appropriate transition education and care before transition to adult care in order to increase adaptation to adult care, to gain self-management skills and to reduce their concerns. Studies in which adolescents are followed up after transition to adult care show that when the transition process is not successfully completed, there is excessive time between the last pediatric control and the first adult control or there are losses in further follow-up. Although there are studies in our country in which transition care is applied, this study is planned because there is no intervention study in which developmental transition care model is applied to adolescents with congenital heart disease. It is thought that this study will increase the transition readiness levels, self-management skills and care satisfaction of adolescents with congenital heart disease and guide the nurses working with them.