Abstract Background It was aimed to investigate the psychological effects of the Coronavirus disease 2019 (COVID-19) pandemic on children and adolescents. The effects of disease process on development of psychiatric disorders, the course of pre-existing disorders, and peer relationships of children who have had COVID-19 infection were evaluated. Fifty three patients (28 girls and 25 boys) who were aged 12 ± 2.64 years and diagnosed with COVID-19 infection within the last 3–9 months, were randomly selected and included. Sociodemographic form, Beck Depression Inventory/Children’s Depression Scale, Symptom Checklist 90-Revised were given to the participants, and a semi-structured interview was used to establish psychiatric disorders before and after COVID-19 infection. Parents were asked to fill in Conner’s Rating Scale-Parents and Behavioral Rating Inventory of Executive Function. Results Compared to pre-pandemic, duration of physical activity and time spent with peers were decreased, while screen exposure was found to be increased. Subclinical psychiatric symptoms were exacerbated after infection and most affected area was eating problems with loss of appetite and weight. Conclusions In conclusion, our data showed that COVID-19 is associated with an increase in psychiatric disorders among children and adolescents, and further studies are needed in a larger population to investigate the causes and consequences of these effects.