IMPORTANCE: Injuries are a major cause of morbidity and mortality among children with neurodevelopmental conditions. Identifying injuries associated with this vulnerable population could inform specific preventive actions. OBJECTIVE: To compare the injury risk among children with autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), or coexisting ASD and ADHD with children with typical development (TD). DESIGN, SETTING, AND PARTICIPANTS: This population-based cohort study involved 325 412 children born between 2005 and 2009, followed up until the end of 2021. Data analysis was conducted from February 2 to November 14, 2023. The study data were extracted from the Clalit Health Service (CHS) database, which contains comprehensive clinical and sociodemographic data on all members of the CHS admitted to the emergency departments (EDs) of all hospitals in Israel during the study period. Children who were members of CHS born between 2005 and 2009 were classified into 4 groups: ASD, ADHD, ASD and ADHD, and TD (control). MAIN OUTCOMES AND MEASURES: Negative binomial regression models were used to assess incidence rate ratios (IRRs) of ED visits between the study groups and the control group. These models were adjusted for birth year, sector, and socioeconomic status. IRRs for specific injuries were also assessed. The statistical significance of IRRs was assessed using 95% CIs. RESULTS: A total of 325 412 children (163 183 boys [50%]) were included in the study. Children with ASD, ADHD, or both had significantly higher ED visit rates than children with TD (IRR, 1.48 [95% CI, 1.42-1.55], 1.45 [95% CI, 1.39-1.52], and 1.29 [95% CI, 1.28-1.30], respectively). Children with ADHD had also higher rates of ED visits due to physical injuries compared with controls (IRR, 1.18 [95% CI, 1.16-1.20]), whereas children with ASD with or without ADHD did not (IRR, 0.96 [95% CI, 0.89-1.05] and 0.91 [95% CI, 0.83-1.00], respectively). A focused analysis of the injury profiles revealed that children with ASD or comorbid ASD and ADHD had higher rates of ingestion and inhalation injuries (IRR, 1.57 [95% CI, 1.06-2.25] and 1.80 [95% CI, 1.28-2.48], respectively) and lower rates of orthopedic injuries (IRR, 0.78 [95% CI, 0.69-0.89] and 0.83 [95% CI, 0.74-0.93], respectively), and animal-inflicted injuries (IRR, 0.44 [95% CI, 0.22-0.79] and 0.92 [95% CI, 0.60-1.35], respectively) than controls. CONCLUSIONS AND RELEVANCE: In this large cohort study, different types of injury were associated with children with ASD and ADHD. The causes underlying these associations should be further investigated to develop effective approaches for injury reduction among these children.