OBJECTIVE: Despite limited evidence for generalized use, high-flow nasal cannula (HFNC) use continues to increase in acute respiratory illnesses. We aimed to reduce HFNC length of treatment (LOT) and length of stay (LOS) by 10% for patients aged 1 month to 5 years with bronchiolitis, pneumonia, or asthma receiving HFNC in the emergency department, pediatric floor, or pediatric intensive care unit. METHODS: Using quality improvement (QI) methods, a multidisciplinary team implemented a weaning algorithm incorporating rapid weaning and discontinuation of HFNC at weight-based flow rates (Holiday). Primary outcome measures were LOT and LOS. Process measures included mean weight-based flow rate at HFNC discontinuation and Holiday occurrences. Balancing measures included readmission rates and positive pressure ventilation (PPV) following a Holiday. Intervention impact was monitored using run charts and statistical process control charts. RESULTS: A total of 430 patient encounters were included, with 281 in the baseline phase and 149 in the improvement phase. Mean LOT decreased from 55.7 to 39.7 hours. Mean LOS decreased from 94.3 to 70.6 hours. Mean weight-based flow rate at HFNC discontinuation increased from 0.6 L/kg/min to 0.9 L/kg/min. Holiday occurrences increased from 10.9% to 82.8%. All improvements showed nonrandom signal or special cause variation (SCV) on control charts. Use of PPV and readmissions were uncommon before and after the intervention. CONCLUSIONS: Using QI methodology to implement a weaning algorithm with rapid discontinuation of HFNC at weight-based flow rates for patients with bronchiolitis, pneumonia, and asthma was associated with a 29% reduction in LOT and 25% reduction in LOS.