Objectives/Hypothesis To identify risk factors for postoperative respiratory events in pediatric patients with severe obstructive sleep apnea (OSA). Methods Retrospective single‐institution retrospective cohort study of pediatric patients with severe OSA who were admitted postoperatively after tonsillectomy. Patients who experienced respiratory events after surgery were identified and differences between the respiratory event and no event groups were compared. Results There were 887 patients included in this study. 14.8% (n = 131) experienced a documented respiratory event. The following risk factors were found to be most significant: %sleep time with O2 < 90% (tb90) (95% CI = 1.07–1.14, OR = 1.10, p < 0.001), Black race (95% CI = 1.53–3.58, OR = 2.34, p < 0.001), primary neurologic co‐morbidity (1.67–6.32, OR = 3.27, p < 0.001), Down syndrome (1.25–5.94, OR = 2.72, p = 0.01), and age (0.84–0.94, OR = 0.88, p < 0.001). Regression modeling demonstrated that the rate of respiratory events increased with tb90. Conclusions Our results demonstrate that there are other potential risk factors outside of AHI and O2 nadir that are associated with respiratory events after tonsillectomy. Black race and prolonged desaturations during polysomnography (PSG) are independent risk factors. Measures of abnormal gas exchange on PSG may be better at identifying at risk patients. Level of Evidence 4 Laryngoscope, 133:1251–1256, 2023 This is a retrospective single‐institution cohort study of pediatric patients with severe obstructive sleep apnea who were admitted postoperative after tonsillectomy. We identified multiple potential risk factors for postoperative respiratory events including Black ethnicity, Down syndrome, age, %sleep time with SpO2 <90% on sleep study.