ObjectiveTo determine if body mass index (BMI) is predictive of adverse respiratory events (ARE) in the obese pediatric population undergoing tonsillectomy.Study DesignCase series with chart review.SettingSingle institution academic otolaryngology practice.MethodsAll patients 3 to 12 years old with BMI ≥95th percentile that underwent tonsillectomy March 1, 2011 to July 15, 2020 were included. The study excluded patients with comorbidities that warranted admission independent of BMI, including Trisomy 21, gross developmental delay, neuromuscular disorders, and congenital heart disease. Perioperative AREs following tonsillectomy were recorded. AREs were defined as postoperative desaturation (SpO2 < 90%), intubation, continuous positive airway pressure (CPAP), or new O2 requirement for >2 hours.ResultsEighteen patients (8%) had at least 1 ARE. There were no children age 5 and older with a BMI 95th percentile to 98.9th percentile who had an early adverse respiratory outcome. Preoperative polysomnogram (PSG) metrics, obstructive apnea‐hypopnea index (oAHI), and oxygen saturations (SpO2) nadir was significantly different between patients with and without AREs (mean oAHI 54.3 vs 17.4, P = .02; mean SpO2 nadir 73.1% vs 84.5%, P = .05). There was no significant difference in the BMI z score (2.88 vs 2.45, P = .09) between groups.ConclusionAREs requiring inpatient management are uncommon in obese children after tonsillectomy. BMI is a poor independent indication for admission except at BMI extremes. We found significantly higher oAHI and lower SpO2 nadir on PSG indicate a higher risk for AREs and can guide admission postoperatively. There may be a subset of obese tonsillectomy patients who can be safely discharged home on the day of surgery.