Background: We aimed to examine temporal changes in the annual rate of acute kidney injury (AKI) in Danish children and associated changes in patient characteristics including potential underlying risk factors. Methods: In this population-based cohort study, we used plasma creatinine measurements from Danish laboratory databases to identify AKI episodes in children aged 0–17 years from 2007 to 2021. For each child, the first AKI episode per calendar year was included. We estimated the annual crude and sex- and age-standardized AKI rate as the number of children with an AKI episode divided by the total number of children as reported by census numbers. Using Danish medical databases, we assessed patient characteristics including potential risk factors for AKI, such as use of nephrotoxic medication, surgery, sepsis, and perinatal factors. Results: In total, 14,200 children contributed with 16,345 AKI episodes over 15 years. The mean annual AKI rate was 148 (95% CI: 141–155) per 100,000 children. From 2007 to 2021, the annual AKI rate demonstrated minor year-to-year variability without any discernible overall trend. The highest AKI rate was recorded in 2007 at 174 (95% CI: 161–187) per 100,000 children, while the lowest rate occurred in 2012 at 129 (95% CI: 118–140) per 100,000 children. In 2021, the AKI rate was 148 (95% CI: 141–155) per 100,000 children. Characteristics of children with AKI were similar throughout the study period. Conclusion: The rate of AKI among Danish children was stable from 2007 to 2021 with little variation in patient characteristics over time. [ABSTRACT FROM AUTHOR]