The COVID-19 pandemic had a detrimental impact on adolescent mental health, but few studies have explicitly compared adolescents’ mental health across countries, nor have they explored how different uses of media by adolescents in different countries may serve as protective or detrimental factors. To explore these associations, we use data collected from 958 South Korean adolescents and 1,253 United States (U.S.) adolescents in spring 2022 (ages 14–18). U.S. adolescents scored higher on anxiety and loneliness, relative to South Korean adolescents, and U.S.