Rehospitalization following pediatric heart transplantation is common. However, existing data remain somewhat limited. Using a novel linkage between administrative and clinical databases, pediatric heart transplant (HT) recipients from 29 centers who survived to discharge were retrospectively reviewed to determine the frequency, timing of, and indication for all-cause rehospitalizations in the year following transplant discharge. Of 2870 pediatric HT recipients, 1835 (63.9%) were rehospitalized in the first year post-discharge (5429 total readmissions). Rehospitalization rates varied significantly across centers (46% to 100%) and were inversely correlated to center transplant volume (r² 0.25, p < 0.01). The median number of rehospitalizations per patient was 2 (IQR 1–4) and the median time to first rehospitalization was 29 days (IQR 9–99 days). Independent risk factors for rehospitalization included younger age at HT (HR 0.99, 95% CI 0.97–0.99), congenital heart disease (HR 1.2, 95% CI 1.1–1.4), listing status 1B at transplant (HR 1.3, 95% CI 1.1–1.5), and post-transplant complications including rejection prior to discharge (HR 1.5 95% CI 1.3–1.8) and chylothorax (HR 1.3, 95% CI 1.0–1.6). Cardiac diagnoses were the most common indication for rehospitalization (n = 1600, 29.5%), followed by infection (n = 1367, 25.2%). These findings may serve to guide the development of interventions aimed at reducing post-HT hospitalizations.