Abstract Background The COVID‐19 pandemic negatively affected child and adolescent mental health and at the end of the pandemic (April 2022) child mental health had not returned to pre‐pandemic levels. We investigated whether this observed increase in mental health problems has continued, halted, or reversed after the end of the pandemic in children from the general population and in children in psychiatric care. Methods We collected parent‐reported and child‐reported data at two additional post‐pandemic time points (November/December 2022 and March/April 2023) in children (8–18 years) from two general population samples ( N = 818–1056 per measurement) and one clinical sample receiving psychiatric care ( N = 320–370) and compared these with data from before the pandemic. We collected parent‐reported data on internalizing and externalizing problems with the Brief Problem Monitor and self‐reported data on Anxiety, Depressive symptoms, Sleep‐related impairments, Anger, Global health, and Peer relations with the Patient‐Reported Outcomes Measurement Information System (PROMIS ® ). Results In the general population, parents reported no changes in externalizing problems but did report higher internalizing problems post‐pandemic than pre‐pandemic ( p < 0.001). Children also reported increased mental health problems post‐pandemic, especially in anxiety and depression, to a lesser extent in sleep‐related impairment and global health, and least in anger (all p s < 0.01). In the clinical sample, parents reported higher internalizing ( p < 0.001), but not externalizing problems post‐pandemic compared to the start of the pandemic. Children reported greatest increases in problems in anxiety, depression, and global health, to a lesser extent on sleep‐related impairment, and least on anger (all p s < 0.05). Conclusions Child mental health problems in the general population are substantially higher post‐pandemic compared to pre‐pandemic measurements. In children in psychiatric care mental health problems have ...