This study aimed to examine the impact of maternal depressive symptoms trajectories on 15-year-old adolescents’ self-esteem and emotion regulation and test the mediating role of child maltreatment in this association. The 2004 Pelotas Birth Cohort is an ongoing cohort study originally comprised of 4231 live births in a southern Brazilian city. We examined a subsample of 1949 adolescents at age 15 years. Maternal depressive symptoms were assessed using the Edinburgh Postnatal Depression Scale. Trajectories of maternal depression from 3 months until the 11-year follow-up were calculated using a group-based modeling approach. Child maltreatment at age 11 years was measured using the parent-report version of the Parent–Child Conflict Tactics Scale. Adolescent outcomes at age 15 years were assessed by the self-report version of the Rosenberg Self-esteem Scale and the Emotion Regulation Index for Children and Adolescents. Path model analysis was conducted using a structural equation modeling framework in Mplus software. All maternal depression trajectories were negatively associated with offspring self-esteem and emotion regulation compared to the reference group (low depression trajectory). There was a significant indirect effect of maternal depression trajectories on emotion regulation mediated via child maltreatment. No evidence of moderation by sex was found for any pathway. The effects of maternal depression on adolescents’ emotion regulation are partly mediated by child maltreatment at age 11.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00787-022-02022-6.