IMPORTANCE: Extubation failure (EF) after pediatric cardiac surgery is associated with increased morbidity and mortality. OBJECTIVES: We sought to describe the risk factors associated with early (< 48 hr) and late (48 hr ≤ 168 hr) EF after pediatric cardiac surgery and the clinical implications of these two types of EF. DESIGN SETTING AND PARTICIPANTS: Retrospective cohort study using prospectively collected clinical data for the Pediatric Cardiac Critical Care Consortium (PC4) Registry. Pediatric patients undergoing Society of Thoracic Surgeons benchmark operation or heart transplant between 2013 and 2018 available in the PC4 Registry were included. MAIN OUTCOMES AND MEASURES: We analyzed demographics and risk factors associated with EFs (primary outcome) including by type of surgery. We identified potentially modifiable risk factors. Clinical outcomes of mortality and length of stay (LOS) were reported. RESULTS: Overall 18,278 extubations were analyzed. Unplanned extubations were excluded from the analysis. The rate of early EF was 5.2% (948) and late EF was 2.5% (461). Cardiopulmonary bypass time, ventilator duration, airway anomaly, genetic abnormalities, pleural effusion, and diaphragm paralysis contributed to both early and late EF. Extubation during day remote from shift change and nasotracheal route of initial intubation was associated with decreased risk of early EF. Extubation in the operating room was associated with an increased risk of early EF but with decreased risk of late EF. Across all operations except arterial switch, EF portrayed an increased burden of LOS and mortality. CONCLUSION AND RELEVANCE: Both early and late EF are associated with significant increase in LOS and mortality. Study provides potential benchmarking data by type of surgery. Modifiable risk factors such as route of intubation, time of extubation as well as treatment of potential contributors such as diaphragm paralysis or pleural effusion can serve as focus areas for reducing EFs.