Background: Patients with congenital heart disease (CHD) are increasingly surviving to adulthood. Given their age- and condition-specific needs, the optimal postoperative setting for these patients is not yet determined. This study aims to evaluate the utility of an adult-specific order set in improving clinical outcomes for these patients in a pediatric cardiovascular intensive care unit (ICU). Methods: Adults with CHD (ACHD) admitted to the cardiovascular ICU following cardiac surgery at a pediatric tertiary care center were identified for a retrospective cohort study. Health care delivery metrics and clinical outcomes of participants who received the adult-specific order set were compared with control patients admitted prior to the intervention. Categorical outcomes were compared using the χ2 test of independence or Fisher exact test, and continuous outcomes were assessed using the t test. Results: A total of 130 ACHD patients received the intervention, with no significant differences observed in clinical outcomes when compared with 89 controls. While there was additionally no reduction in hospital-related mortality (2.3% vs 7.8%, RR 0.3; P = .1), clinician ordering behaviors were better aligned with best-practices following the intervention. Among patients with moderate or greater anatomic complexity, a post hoc analysis demonstrated reduced in-hospital mortality from those who received the adult order set. Conclusions: The implementation of an adult-specific order set in a pediatric care setting did not improve clinical outcomes for all ACHD patients. Patients with moderate and greater anatomic complexity did see a mortality benefit, suggestive that targeted electronic tools may most benefit those who have the highest risk.