Respiratory infections trigger asthma exacerbations. Despite being less severely affected by COVID-19 than adults, the subsequent lockdowns had a great impact on children. Previous studies showed a decrease in asthma exacerbations during the COVID-19 lockdowns, but findings from secondary care settings are scarce. We aimed to elucidate the trends in frequency and characteristics of asthma exacerbations in children presenting on an emergency department (ED) of a secondary care setting before, during, and after the COVID-19 pandemic. A retrospective analysis was conducted using data from ED visits between January 2018 and November 2022 for asthma exacerbations in children. The incidence of ED visits, hospital admissions, paediatric intensive care unit (PICU) admissions, administered medication, and demographic information were compared. A total of 1121 exacerbations were reported in 670 children, of whom 476 (42%) were admitted to hospital and 44 (3.9%) required PICU admission. We observed a decrease in ED visits for asthma exacerbations during the pandemic but an increased risk in hospital admissions and PICU transfers for exacerbations. This suggests a more severe course of exacerbations. Barriers to health care and lower viral exposure may contribute to this.