Abstract Background Influenza virus and SARS-CoV-2 are significant causes of respiratory illness in children. Methods Influenza- and COVID-19–associated hospitalizations among children <18 years old were analyzed from FluSurv-NET and COVID-NET, 2 population-based surveillance systems with similar catchment areas and methodology. The annual COVID-19–associated hospitalization rate per 100 000 during the ongoing COVID-19 pandemic (1 October 2020–30 September 2021) was compared with influenza-associated hospitalization rates during the 2017–2018 through 2019–2020 influenza seasons. In-hospital outcomes, including intensive care unit (ICU) admission and death, were compared. Results Among children <18 years, the COVID-19–associated hospitalization rate (48.2) was higher than influenza-associated hospitalization rates: 2017–2018 (33.5), 2018–2019 (33.8), and 2019–2020 (41.7). The COVID-19–associated hospitalization rate was higher among adolescents 12–17 years old (COVID-19: 59.9; influenza range: 12.2–14.1), but similar or lower among children 5–11 (COVID-19: 25.0; influenza range: 24.3–31.7) and 0–4 (COVID-19: 66.8; influenza range: 70.9–91.5) years old. Among children <18 years, a higher proportion with COVID-19 required ICU admission compared with influenza (26.4% vs 21.6%; P < .01). Pediatric deaths were uncommon during both COVID-19– and influenza-associated hospitalizations (0.7% vs 0.5%; P = .28). Conclusions In the setting of extensive mitigation measures during the COVID-19 pandemic, the annual COVID-19–associated hospitalization rate during 2020–2021 was higher among adolescents and similar or lower among children <12 years compared with influenza during the 3 seasons before the COVID-19 pandemic. COVID-19 adds substantially to the existing burden of pediatric hospitalizations and severe outcomes caused by influenza and other respiratory viruses.