New Zealand research on inequities in children's developmental health outcomes is sparse. We aimed to describe the prevalence, clustering, and socio-environmental associations of developmental health in preschool-aged children. A latent profile analysis was performed using data from child participants of at age 4.5-years to identify profiles of developmental health status. Seven measures were included in the latent profile analysis, representing four domains of developmental health: 'physical', 'motor', 'socioemotional and behavioural', and 'communication and learning'. Multinominal logistic regression was used to investigate socio-environmental associations of latent profile membership. Six latent profiles were identified ( = 6109), including three healthy/flourishing profiles: 'healthy' (52.6% of the sample), 'early social skills flourishing' (14.5%), and 'early learning skills flourishing' (4.0%); and three suboptimal profiles: 'early learning skills difficulties' (19.5%), 'physical health difficulties' (5.6%), and 'developmental difficulties cluster' (3.7%). Children experiencing socioeconomic disadvantage, of Māori or Pacific ethnicity, and with unmet healthcare needs had increased odds of being classified to suboptimal developmental health profiles. In this large, diverse cohort, one-in-four children were classified as having suboptimal developmental health. Addressing inequities in developmental health is crucial to improving health over the life course.