Objective: We examined associations between developmental vulnerability profiles determined at the age of 5 years and subsequent childhood mental illness between ages 6 and 13 years in an Australian population cohort. Methods: Intergenerational records from New South Wales (NSW) Government Departments of Health and Child Protection spanning pre-birth to 13 years of age were linked with the 2009 Australian Early Development Census records for 86,668 children. Mental illness indices for children were extracted from health records between 2009 and 2016 (child’s age of 6–13 years). Associations between mental disorder diagnoses and membership of early childhood risk groups, including those with established ‘special needs’ (3777, 4.3%) at school entry, or putative risk classes delineated via latent class analysis of Australian Early Development Census subdomains – referred to as ‘pervasive risk’ (N = 3479; 4.0%), ‘misconduct risk’ (N = 5773; 6.7%) or ‘mild generalised risk’ (N = 9542; 11%) – were estimated using multinomial logistic regression, relative to children showing ‘no risk’ (N = 64,097; 74%). Poisson regression models estimated the relative risk of a greater number of days recorded with mental health service contacts among children in each Australian Early Development Census risk group. Adjusted models included child’s sex, socioeconomic disadvantage, child protection contacts and parental mental illness as covariates. Results: The crude odds of any mental disorder among children aged 6–13 years was increased approximately threefold in children showing pervasive risk or misconduct risk profiles at the age of 5 years, and approximately sevenfold in children with special needs, relative to children showing no risk; patterns of association largely remained after adjusting for covariates. Children with special needs and the misconduct risk class used mental health services over a greater number of days than the no risk class. Conclusion: Patterns of early childhood developmental vulnerability are associated with subsequent onset of mental disorders and have the potential to inform interventions to mitigate the risk for mental disorders in later childhood and adolescence.