Background: Several case series have described the clinical characteristics of COVID-19 in pediatric patients and suggest milder illness severity in children compared with adults. However, some cases presented more severe diseases with small numbers of deaths have been documented. Some studies in developed countries demonstrated that the presence of comorbidities among COVID-19 patients could increase the severity of the disease. Therefore, this study aimed to identify the association of comorbidities with mortality and severity among children with COVID-19. Methods: This was an analytic retrospective cross-sectional study conducted in Prof. Dr. IGNG Ngoerah Hospital, Denpasar, from May 2020 until March 2022. A total of 94 children aged 28 days-18 years old with confirmed COVID-19 were included in this study and divided into two groups, with comorbidities and without comorbidities. The chi-square test was used to determine the association between comorbidities and their relation to mortality and severity. The statistical significance was set at p less than 0.05. Results: The normality test showed that the age data distribution is not normal with the median age of 72 months (IQR 45-189) and 108 months (IQR 64-240) in the comorbidities and without comorbidities group, respectively. Bivariate analysis showed there was a significant association between comorbidities with the mortality and severity among children with COVID-19 (PR 3.21; 95% CI 1.04-9.90; p= 0.036) and (PR 10.71; 95%CI 4.12-27.83; p< 0.001), respectively. The multivariate analysis revealed the comorbidities increased risk of mortality and severity with adjusted OR (aOR) 3.74 (95%CI 1.14-12.25) and adjusted OR (aOR) 11.8 (95%CI 4.35-32.41), respectively; after adjusting for age and nutritional status. Conclusion: Comorbidities significantly affect mortality and severity among children with COVID-19.