To assess whether the association of adverse childhood experiences (ACEs) with pediatric health care utilization differs by age. In this retrospective cohort study, we included patients completing primary care ACEs screening between January 2020 and September 2021. Pediatric ACEs and Related Life Events Screener Part 1 scores were categorized 0, 1 to 3, or ≥4 (none, low, and high, respectively). Two multivariable logistic regression models assessed emergency department (ED) and inpatient utilization across all ages 6 months after screening. Among 37 315 patients, 15.7% visited the ED and 2.5% were hospitalized within 6 months of ACEs screening. Using no ACEs as the reference, infants and toddlers with any ACEs had lower odds of ED and inpatient utilization, whereas older children with any ACEs had higher odds of ED (age-low ACEs: 0.04, P value < .001; age-high ACEs: 0.08, P value < .001) and inpatient (age-low ACEs: 0.06, P value < .001; age-high ACEs: 0.15, P value < .001) utilization and increased each successive year of age. The association of ACEs with health care utilization is dependent on age and is more complex than previously described. These trends may inform specific therapeutic strategies for pediatric patients by age.