<p>More than six decades ago, the first successful repair of a congenital heart defect opened a new frontier in pediatric medicine. Driven by advances in fetal imaging, computational fluid dynamics, machine learning, and surgical perfusion, our ability to diagnose and treat these conditions has grown remarkably. Many of today’s greatest challenges in congenital cardiology - early and accurate diagnosis, precise risk stratification, and lifelong management - are increasingly being addressed through methods borrowed from engineering and data science. The Congenital heart defects: Diagnosis and treatment Collection at Scientific Reports is dedicated to this research.</p>