Background Exclusion from school is increasingly recognized as pertinent to child health. National educational data reveal that boys, children who are looked‐after, living in poverty, have special educational needs, or from certain ethnic minorities, are disproportionately excluded from school. As population‐based data on the wider characteristics of excluded children are scarce, we aimed to describe predictors of school exclusion in the Avon Longitudinal Study of Parents and Children. Method Avon Longitudinal Study of Parents and Children, a prospective U.K. population‐based birth cohort study, collected parent reports of permanent school exclusions by 8 years and parent and self‐reports of permanent and fixed‐term exclusions in the preceding 12 months at 16 years. Potential risk factors were examined for associations with exclusion using logistic regression, with a focus on child mental health and neurodevelopment. Results Analyses were based on all available data on 53/8,245 (0.6%) pupils excluded from school by 8 years and 390/4,482 (8.7%) at 16 years. Key factors associated with exclusion at both time points included male gender, lower socio‐economic status, maternal psychopathology, mental health and behavioural difficulties, psychiatric disorder, social communication difficulties, language difficulties, antisocial activities, bullying/being bulled, lower parental engagement with education, low school engagement, poor relationship with teacher, low educational attainment, and special educational needs (all p < .05). Conclusion Exclusion from school was associated with child, family and school‐related factors identifiable at, or prior to, primary school age. Child health professionals have an important role in the holistic, multidisciplinary assessment of children who are at risk of exclusion from school. Mental health and neurodevelopmental difficulties should be recognized and supported, to improve the health and educational outcomes among this vulnerable group.