BACKGROUND: Children with congenital heart defects (CHD) have an increased risk of developmental delay. It remains sparsely investigated if these patients also have a delayed pubertal development. In this nationwide cohort study, we evaluated if CHD was associated with timing of puberty using longitudinally collected data on pubertal milestones. METHODS AND RESULTS: We used data from the Danish nationwide Puberty Cohort. Information on CHD was obtained from the Danish National Patient Register. Information on pubertal development was obtained from 15 780 children through questionnaires answered half-yearly from 11 years until 18 years or full maturity. Using a multivariable regression model for censored time-to-event data, mean difference in age at attaining each pubertal milestone was estimated, including a combined pubertal marker. Compared with children without CHD, analyses were performed for both CHD overall and subdivided into simple and complex CHD. In a subanalysis, analyses were repeated in children born at term. In total, 137 children (62 boys and 75 girls) had a CHD diagnosis. Overall, no difference in age at pubertal timing was observed for children with CHD compared with unaffected children. The average differences were small for both boys (1.6 [95% CI, −2.6 to 5.7] months) and girls (1.0 [95% CI, −2.5 to 4.4] months). The same differences were observed when subdividing into simple or complex CHD and when restricting to children born at term. CONCLUSIONS: We found no association between CHD and pubertal timing. For the group of children with complex CHD, we were unable to exclude a later pubertal timing.