Objective: The novel coronavirus disease 2019 (COVID-19) pandemic, and its resulting social policy changes, may result in psychological distress among schoolchildren with overweight. This study thus aimed to (1) compare psychological distress (including fear of COVID-19 infection, stress, anxiety, and depression), perceived weight stigma, and problematic internet-related behaviors between schoolchildren with and without overweight; (2) assess whether perceived weight stigma and problematic internet-related behaviors explained psychological distress.Methods: Schoolchildren (n=1 357; mean age=10.7 years) with overweight (n=236) and without overweight (n=1 121) completed an online survey assessing their fear of COVID-19 infection, stress, anxiety, depression, perceived weight stigma, problematic smartphone application use, problematic social media use, and problematic gaming.Results: Schoolchildren with overweight had significantly higher levels of COVID-19 infection fear, stress, depression, perceived weight stigma, and problematic social media use than those without overweight. Regression models showed that perceived weight stigma and problematic internet-related behaviors were significant predictors of psychological distress among schoolchildren with overweight.Conclusion: Strategies to manage perceived weight stigma and problematic internet-related behaviors may have a positive influence on mental health among schoolchildren with overweight under health-threatening circumstances, such as the current COVID-19 pandemic.