Background: Maternal diet quality during pregnancy has been linked to offspring's physical and mental health outcomes across the lifespan. However, few studies have examined its association with subsequent offspring's anxiety and depression issues. Objectives: The objective of the study was to examine the relationship between maternal prenatal dietary patterns and offspring's anxiety and depression symptoms from 3 to 8 years. Methods: We used data from 1242 children enrolled in the French EDEN (Etude des déterminants pré- et postnatals précoces du développement et de la santé de l'enfant) birth cohort. Maternal third trimester dietary patterns-namely, "Healthy" (i.e., high intake in fruit, vegetables, fish, and whole-grain cereals) and "Western" (i.e., high intake in processed and snacking foods) patterns-were evaluated using a validated qualitative FFQ. Children's anxiety and depression symptoms (i.e., fears, worries, misery, nervousness, and somatic symptoms) were assessed by mothers using the Strengths and Difficulties Questionnaire at ages 3, 5, and 8 years, from which trajectories were derived using group-based trajectory modeling. We used logistic regressions to analyze the associations between maternal dietary patterns and children's anxiety and depression symptom trajectories. Results: We identified 2 trajectories of anxiety and depression symptoms from 3 to 8 years of age: low to moderate (n = 1058; reference group) and moderately high (n = 184). Maternal low adherence to the Healthy dietary pattern in the third trimester was significantly associated with moderately high children's anxiety and depression symptom trajectories from 3 to 8 years (OR, 1.87; 95% CI, 1.40-2.51), in crude and adjusted analyses. The maternal Western dietary pattern was not significantly associated with anxiety and depression symptom trajectories. Conclusions: High maternal prenatal adherence to a Healthy dietary pattern was negatively related to anxiety and depression symptoms in children. As maternal diet is a key lifestyle factor, further research should investigate its association with subsequent offspring anxiety and depression symptoms in aiming to later inform prevention strategies focusing on pregnancy.