To assess the incidence and clinical characteristics of acute kidney injury (AKI) and identify the associated risk factors for AKI in children with type 1 diabetes mellitus (T1DM) and diabetic ketoacidosis (DKA). This was a retrospective study performed over 15 y in a single Korean center. Children aged ≤18-y-old with T1DM and DKA were enrolled and divided into 2 groups according to the presence of AKI. This study included 90 episodes of DKA in 58 children with T1DM. AKI occurred in a total of 70 hospitalizations (77.8%) of 44 children: 18 (20.0%) with stage 1 AKI, 39 (43.3%) with stage 2 AKI, and 13 (14.4%) with stage 3 AKI. The number of AKI decreased to 28 (47.4%) and 13 (28.3%) after 12 h and 24 h of admission, respectively. The white blood cell count (P = 0.001) and anion gap levels (P = 0.025) were significantly higher and serum bicarbonate level (P = 0.004) was lower in the AKI group. Logistic regression analysis revealed that a longer duration of TIDM and high anion gap were independent predictors of developing severe AKI in pediatric DKA with T1DM (odds ratio, 1.225, P = 0.013; odds ratio, 1.130, P = 0.038). AKI frequently occurred in TIDM children with DKA. Longer duration of TIDM and elevated anion gap are associated with occurrence of severe AKI.