BackgroundChildren with congenital heart disease (CHD) are thought to have low levels of physical activity (PA), but few studies have used objective measures of PA in this population.Methods and ResultsWe recruited patients with mild, moderate, and severe CHD and cardiac transplant recipients, aged 8 to 19 years, from pediatric cardiology clinics throughout British Columbia and Yukon, Canada. Participants were fitted with an ActiGraph accelerometer to be worn over the right hip for 7 days. Daily means were estimated for a variety of accelerometry‐derived metrics, including moderate‐to‐vigorous PA and percentage of sedentary time if they had at least 3 valid days of accelerometry data. Participants also completed a PA questionnaire. We included 90 participants (aged 13.6±2.7 years; 54% male), of which 26 had mild CHD, 26 had moderate CHD, 29 had severe CHD, and 9 were cardiac transplant recipients. Median daily moderate‐to‐vigorous PA was 43 min/day (interquartile range: 28.9–56.9 min/day), and 8% met PA guidelines of 60 minutes of moderate‐to‐vigorous PA at least 6 days a week. There were no significant differences in any accelerometry‐derived metric according to CHD severity. Boys were significantly more active and less sedentary than girls. Activity declined and sedentary behaviors increased with age in both sexes. Sports participation was common, including competitive out‐of‐school clubs (57%). PA restrictions from cardiologists were rare (15%).ConclusionsWe found normal age–sex patterns of PA in children with CHD. There were no differences in PA by CHD severity, suggesting that sociocultural factors are likely important determinants of PA in these children.