Summary The association between body mass index (BMI) and poor COVID‐19 outcomes in patients has been demonstrated across numerous studies. However, obesity‐related comorbidities have also been shown to be associated with poor outcomes. The purpose of this study was to determine whether BMI or obesity‐associated comorbidities contribute to elevated COVID‐19 severity in non‐elderly, hospitalized patients with elevated BMI (≥25 kg/m2). This was a single‐center, retrospective cohort study of 526 hospitalized, non‐elderly adult (aged 18–64) COVID‐19 patients with BMI ≥25 kg/m2 in suburban New York from March 6 to May 11, 2020. The Edmonton Obesity Staging System (EOSS) was used to quantify the severity of obesity‐related comorbidities. EOSS was compared with BMI in multivariable regression analyses to predict COVID‐19 outcomes. We found that higher EOSS scores were associated with poor outcomes after demographic adjustment, unlike BMI. Specifically, patients with increased EOSS scores had increased odds of acute kidney injury (adjusted odds ratio [aOR] = 6.40; 95% CI 3.71–11.05), intensive care unit admission (aOR = 10.71; 95% CI 3.23–35.51), mechanical ventilation (aOR = 3.10; 95% CI 2.01–4.78) and mortality (aOR = 5.05; 95% CI 1.83–13.90). Obesity‐related comorbidity burden as determined by EOSS was a better predictor of poor COVID‐19 outcomes relative to BMI, suggesting that comorbidity burden may be driving risk in those hospitalized with elevated BMI.