Introduction <p>In France, 10% of the population are immigrants and another 11% are children of immigrants. Both have worse mental health than the native French. The role of adverse childhood experiences (ACE) in immigrants’ mental health is not well characterized. We aimed to examine associations between immigration background, ACEs, and depressive symptoms.</p> Methods <p>Data came from the baseline and 2020 follow-up questionnaires of the French CONSTANCES study (<i>n</i> = 116,495), a national cohort. The exposure was immigration background categorized by immigration generation (1st : immigrants; 2nd : French-born with ≥ 1 immigrant parent; and native French) and the geographic origin of the participant (1st generation) or ≥ 1 parent (2nd generation). The mediator was experiencing ACEs. The outcome was depressive symptoms ascertained with the Center for Epidemiologic Studies Depression scale at study inclusion. Mediation analysis using multivariable logistic regression and path analysis (PA) was used to assess associations between the exposure, mediator, and outcome, overall and stratified by sex, minimally adjusting for age and sex or adjusting for all covariates.</p> Results <p>The prevalence of depressive symptoms was 18.5%. In minimally adjusted models, compared to native French, there were higher odds of depressive symptoms in 1st and 2nd generation adults except those with ≥ 1 parent from Asia. Mediation effects of ACEs from PA ranged from 0.03 to 0.10. In the fully adjusted model including after adjusting for experiencing ACEs, only immigrants from North Africa had significantly increased odds of depressive symptoms (AOR = 1.52, 95%CI: 1.29, 1.79).</p> Conclusions <p>In France, non-native adults have higher prevalence and odds of depressive symptoms than the native French, with ACEs having a significant mediating effect.</p>