Numerous studies have provided evidence for the negative associations of the COVID-19 pandemic with mental health, but data on the use of psychotropic medication in children and adolescents after the onset of the COVID-19 pandemic are lacking. To assess the rates and trends of psychotropic medication prescribing before and over the 2 years after the onset of the COVID-19 pandemic in children and adolescents in France. This cross-sectional study used nationwide interrupted time-series analysis of outpatient drug dispensing data from the IQVIA X-ponent database. All 8 839 143 psychotropic medication prescriptions dispensed to children (6 to 11 years of age) and adolescents (12 to 17 years of age) between January 2016 and May 2022 in France were retrieved and analyzed. Onset of COVID-19 pandemic. Monthly rates of psychotropic medication prescriptions per 1000 children and adolescents were analyzed using a quasi-Poisson regression before and after the pandemic onset (March 2020), and percentage changes in rates and trends were assessed. After the pandemic onset, rate ratios (RRs) were calculated between estimated and expected monthly prescription rates. Analyses were stratified by psychotropic medication class (antipsychotic, anxiolytic, hypnotic and sedative, antidepressant, and psychostimulant) and age group (children, adolescents). In total, 8 839 143 psychotropic medication prescriptions were analyzed, 5 884 819 [66.6%] for adolescents and 2 954 324 [33.4%] for children. In January 2016, the estimated rate of monthly psychotropic medication prescriptions was 9.9 per 1000 children and adolescents, with the prepandemic rate increasing by 0.4% per month (95% CI, 0.3%-0.4%). In March 2020, the monthly prescription rate dropped by 11.5% (95% CI, -17.7% to -4.9%). During the 2 years following the pandemic onset, the trend changed significantly, and the prescription rate increased by 1.3% per month (95% CI, 1.2%-1.5%), reaching 16.1 per 1000 children and adolescents in May 2022. Monthly rates of psychotropic medication prescriptions exceeded the expected rates by 11% (RR, 1.11 [95% CI, 1.08-1.14]). Increases in prescribing trends were observed for all psychotropic medication classes after the pandemic onset but were substantial for anxiolytics, hypnotics and sedatives, and antidepressants. Prescription rates rose above those expected for all psychotropic medication classes except psychostimulants (RR, 1.12 [95% CI, 1.09-1.15] in adolescents and 1.06 [95% CI, 1.05-1.07] in children for antipsychotics; RR, 1.30 [95% CI, 1.25-1.35] in adolescents and 1.11 [95% CI, 1.09-1.12] in children for anxiolytics; RR, 2.50 [95% CI, 2.23-2.77] in adolescents and 1.40 [95% CI, 1.30-1.50] in children for hypnotics and sedatives; RR, 1.38 [95% CI, 1.29-1.47] in adolescents and 1.23 [95% CI, 1.20-1.25] in children for antidepressants; and RR, 0.97 [95% CI, 0.95-0.98] in adolescents and 1.02 [95% CI, 1.00-1.04] in children for psychostimulants). Changes were more pronounced among adolescents than children. These findings suggest that prescribing of psychotropic medications for children and adolescents in France significantly and persistently increased after the COVID-19 pandemic onset. Future research should identify underlying determinants to improve psychological trajectories in young people.