BACKGROUND: SARS-CoV-2 (COVID-19) continues to be a major public health issue. Obesity is a major risk factor for disease severity and mortality associated with COVID-19. OBJECTIVE: This study sought to estimate the healthcare resource use and cost outcomes in patients hospitalized with COVID-19 in the United States (US) according to body mass index (BMI) class. METHODS: Retrospective cross-sectional study analyzing data from the Premier Healthcare COVID-19 database for hospital length-of-stay (LOS), intensive care unit (ICU) admission, ICU LOS, invasive mechanical ventilator use, invasive mechanical ventilator use duration, in-hospital mortality, and total hospital costs from hospital charge data. RESULTS: After adjustment for patient age, gender, and race, patients with COVID-19 and overweight or obesity had longer durations for mean hospital LOS (normal BMI = 7.4 days, class 3 obesity = 9.4 days,  < .0001) and ICU LOS (normal BMI = 6.1 days, class 3 obesity = 9.5 days,  < .0001) than patients with normal weight. Patients with normal BMI had fewer days on invasive mechanical ventilation compared to patients with overweight and obesity classes 1-3 (6.7 days vs. 7.8, 10.1, 11.5, and 12.4, respectively,  < .0001). The predicted probability of in-hospital mortality was nearly twice that of patients with class 3 obesity compared to patients with normal BMI (15.0 vs 8.1%,  < .0001). Mean (standard deviation) total hospital costs for a patient with class 3 obesity is estimated at $26,545 ($24,433-$28,839), 1.5 times greater than the mean for a patient with a normal BMI at $17,588 ($16,298-$18,981). CONCLUSIONS: Increasing levels of BMI class, from overweight to obesity class 3, are significantly associated with higher levels of healthcare resource utilization and costs in adult patients hospitalized with COVID-19 in the US. Effective treatment of overweight and obesity are needed to reduce the burden of illness associated with COVID-19.