Objective This study aimed to investigate the changes in interpersonal relationships, behavioral patterns, and emotional states of children and adolescents with psychiatric disorders and their caregivers immediately after the coronavirus disease of 2019 (COVID-19) outbreak in Daegu, South Korea.Methods A total of 147 patients and 147 caregivers participated in the Survey for Outing and Time Usage for Child, Adolescent, and Parents and the COVID-19 Visual Analog Scale for Emotion. We classified the patients and their caregivers into the internalizing disorder (ID) and externalizing disorder (ED) groups and compared the changes.Results Parent–child relationships for adolescent patients and caregivers were interrupted, and friend relationships in all participants were disrupted, while sibling relationships improved in adolescent patients. They experienced negative emotional changes. Time spent outdoor decreased and digital screen time increased for all participants. Friend and parent–child relationships were interrupted in the ED group compared to those in the ID group. ED patients experienced negative changes in emotional states, while ID patients showed no significant changes.Conclusion Results are meaningful as a reference for predicting changes in interpersonal relationships and mental status of pediatric psychiatric patients and for determining healthcare system adaptations to allow mental health support during the COVID-19 outbreak.