This study aimed to assess the association of obesity with the severity and outcome of COVID-19 infection. A retrospective observational study was performed from March to September 2020 in Saudi Arabia. Baseline and laboratory data were collected from the inpatient health record system. The cohort was divided into three groups based on body mass index. Following this, the severity and outcome of COVID-19 disease were analyzed between the three groups. Of the 502 COVID-19 cases included, 244 (48.5%) were obese. Obesity was significantly associated with severe (53.5%) or critical (28%) COVID-19 infection (P<0.001) and a higher need for ICU admission (35.8%, P=0.034). Multivariate analysis showed that overweight/obesity was an independent risk factor of severe (P<0.001) as well as critical COVID-19 infection (P=0.026, respectively) and a predictor of a higher risk of ICU admission (P=0.012). Class I obesity was associated with severe-critical COVID-19 disease (33.6%, P=0.042) compared to other obesity classes. Obesity is an independent risk factor for severe-critical COVID-19 infection and a higher risk of ICU admission. Clinicians should give special attention to such populations and prioritize vaccination programs to improve outcomes.