["Autism Research, EarlyView. ", "\nABSTRACT\nChildren and adolescents with autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) often present physical and motor challenges that may compromise health, yet direct comparisons between these neurodevelopmental conditions and typically developing (TD) peers remain limited. This study aimed to examine the physical fitness profiles of these three groups. A total of 1537 school‐aged participants were recruited from mainstream educational settings. The assessment included selected tests from the EUROFIT battery and body mass index (BMI). Composite indices of physical fitness and motor coordination were computed using age‐ and sex‐adjusted Z‐scores. Both the ADHD (n = 80) and ASD (n = 36) groups showed significantly lower cardiorespiratory fitness, balance, and upper‐body coordination compared with TD peers (n = 1413). Lower‐body muscular strength was reduced only in the ASD group, which also performed worse than the ADHD group. Flexibility and BMI distributions did not differ significantly across groups. Plate Tapping and Flamingo Balance test indices were markedly lower in both clinical groups relative to TD peers. Children and adolescents with ADHD and ASD had lower physical fitness than TD peers. Direct comparisons between ADHD and ASD revealed generally similar profiles, except for lower muscular strength in ASD. These findings highlight the need for early screening and tailored interventions to support healthier developmental trajectories and enhance functional outcomes in neurodevelopmental populations.\n"]