Adherence to 24h movement guidelines of ≥60min of physical activity, ≤2h of screen time, and 9-11h of sleep has been shown to benefit cognition, physical and psychosocial health in children aged 5-13y. However, these findings are largely based on cross-sectional studies or small samples. Here we utilize data from the Adolescent Brain Cognitive Development (ABCD) study of 10000+ children aged 9-11y to examine whether adherence to 24h movement guidelines benefit cognition, BMI, psychosocial health and brain morphometric measures at baseline (T1) and 2 years later (T2). After adjustment for sociodemographic confounders in multivariable linear mixed models, we observed better cognitive scores, fewer behavioural problems, lower adiposity levels and greater gray matter volumes in children who met both sleep and screen time recommendations compared to those who met none. Longitudinal follow up further supports these findings; participants who met both recommendations at T1 and T2 evidenced better outcome measures than those who met none, even after controlling for T1 measures. These findings support consideration of integrated rather than isolated movement recommendations across the day for better cognitive, physical, psychosocial and brain health.