Purpose: To identify emotional and behavioural symptoms profiles from early childhood to adolescence, their stability across development and associated factors. Methods: Our sample included 17,216 children assessed at ages 3, 5, 7, 11 and 14 years from the UK Millennium Cohort Study. We used latent profile and latent transition analysis to study their emotional and behavioural profiles from early childhood to adolescence. We included sociodemographic, family and parenting variables to study the effect on latent profile membership and transitions. Results: The number and specific profiles of emotional and behavioural symptoms changed with the developmental stage. We found a higher number of profiles for ages 3, 5, and 14, suggesting greater heterogeneity in the presentation of emotional and behavioural symptoms in early childhood and adolescence compared to late childhood. There was greater heterotypic continuity between ages 3 and 5, particularly in transitions from higher to lower severity profiles. Children exposed to socioeconomic disadvantages were more likely to belong or transition to any moderate or high emotional and behavioural symptoms profiles. Maternal psychological distress and harsh parenting were associated with internalizing and externalizing profiles, respectively. Higher levels of internalizing and externalizing symptoms across development were associated with lower mental wellbeing and higher rates of self-harm and substance use in adolescence. Conclusion: Emotional and behavioural symptoms develop early in life, with levels of heterogeneity and heterotypic stability that change throughout development. These results call for interventions to prevent and treat paediatric mental illness that consider the heterogeneity and stability of symptoms across development.