Access to the emergency department (ED) for acute psychiatric problems, especially for suicide attempts (SA), has increased in the last decade. This increase has exceptionally accelerated after the COVID-19 pandemic. The aim of this project was to study the increase in acute psychiatric care demand of children and adolescents in the short and medium term after the pandemic, in relation to public health measures and in comparison with a pre pandemic reference period. We retrospectively studied 5445 child psychiatric (CP) consultations requested for any reason and for suicide attempt (SA), suicidal ideation (SI) and non-suicidal self-injury (NSSI) in a pediatric ED during three different pandemic periods in Italy (from March 2020 to May 2022) and compared them to a pre-pandemic reference period (from January 2018 to February 2020). Monthly CP consultations for any reason increased significantly by 2.2 times from 70.9 in 2018 to 157 in 2022 (p < 0.001). During the pandemic, monthly CP consultations for any reason increased significantly from 75/month in the first lockdown to 153/month in the second lockdown, remaining stable in the following year. CP consultations for SA increased significantly from 5/month in the first lockdown to 16/month in the second. Consultations for SI increased gradually but significantly from the pre-pandemic period to the end of the pandemic. Juveniles evaluated for SA during the pandemic vs. pre-pandemic more frequently attempted suicide by self-poisoning and less frequently by precipitation, and they were more likely to be diagnosed with a major depressive disorder. CP consultations for any reason and for suicide attempts significantly increased in the decade before the pandemic and peaked in the second lockdown period in Italy.