Maternal depression during pregnancy is associated with elevated risk of anxiety and depression in offspring, but the mechanisms are incompletely understood. Here we conducted a neuroimaging follow-up of a prenatal birth cohort from the European Longitudinal Study of Pregnancy and Childhood (n= 131; 53% women, age 23-24) to test whether deviations from age-normative structural brain development in young adulthood may partially underlie this link. Structural brain age was calculated based on previously published neuroanatomical age prediction models using cortical thickness maps from healthy controls aged 6-89. Brain age gap was computed as the difference between chronological and structural brain age. Participants also completed self-report measures of anxiety and mood dysregulation. Further, mothers of a subset of participants (n= 103, 54% women) answered a self-report questionnaire in 1990-1992 about depressive symptoms during pregnancy. Higher exposure to maternal depressive symptoms in utero showed a linear relationship with elevated brain age gap, which showed a quadratic relationship with anxiety and mood dysregulation in the young adult offspring. Our findings suggest that exposure to maternal depressive symptoms in utero may be associated with accelerated brain maturation and that deviations from age-normative structural brain development in either direction predict more anxiety and dysregulated mood in young adulthood.