Background Little is known about health-related quality of life (HRQoL) in pediatric patients with cardiac rhythm devices. This study aims to compare self- and proxy-reported HRQoL in patients with pacemaker (PM) and implantable cardioverter-defibrillator (ICD) to that in sex- and age-matched healthy controls and to examine predictors for generic and disease-specific HRQoL. Methods The study included 72 PM and ICD patients (39% females) and 72 sex- and age-matched healthy controls from 3 to 18 years of age. HRQoL data was obtained by the PedsQL 4.0 Generic Core Scales and Pediatric Cardiac Quality of Life Inventory. Medical data was collected retrospectively from medical records. Results Patients had significantly lower self- and proxy-reported generic overall HRQoL and lower physical health than healthy controls, and ICD patients also had lower psychosocial health. On multivariate analyses, generic overall HRQoL and physical health was significantly predicted by current cardiac medication (β = −.39, p = .02 for overall HRQoL, respectively β = −.44, p = .006 for physical health). Disease-specific overall HRQoL was only marginally predicted by child age, device type, and the presence of a structural congenital heart disease (p < .10). Conclusions This study shows that PM and ICD patients have lower HRQoL than healthy controls and that patients who need cardiac medication are seen by their parents at great risk for lower generic overall HRQoL. Our study also indicates a trend towards higher risk for low disease-specific HRQoL in younger patients, ICD patients, and patients with a structural congenital heart disease. Special attention should be given to these patients as they may benefit from a timely clinical evaluation in order to provide supportive interventions.