Background <p>This study examined the association of psychological symptoms with adherence to Mediterranean (MED), dietary approach to stop hypertension (DASH), and Mediterranean-DASH intervention for neurodegenerative delay (MIND) diets, and serum 25(OH)D levels in Iranian adults.</p> Methods <p>In this cross-sectional study, 527 adults aged 20–65 years were assessed. Dietary intake was collected using a validated 168-item food frequency questionnaire. Serum 25-hydroxy vitamin D levels were measured, and psychological symptoms were evaluated using standard questionnaires. Multivariable logistic regression was conducted with adjustment for confounders.</p> Results <p>In the fully-adjusted model, subjects in the highest vs. lowest tertile of MED (OR = 0.21; 95%CI: 0.08–0.48), DASH (OR = 0.35; 95%CI: 0.16–0.78), and MIND (OR = 0.20; 95%CI: 0.09–0.45) diets had lower odds of reporting depressive symptoms. Participants in the top vs. bottom tertile of MED (OR = 0.12; 95%CI: 0.02–0.67), DASH (OR = 0.16; 95%CI: 0.03–0.85), and MIND (OR = 0.07; 95%CI: 0.01–0.63) diets also exhibited 88%, 84%, and 93% lower odds of reporting anxiety symptoms. An inverse significant association has been found between the MED diet and odds of distress (OR = 0.39; 95%CI: 0.21–0.72). However, no significant relationship has been found between the DASH and MIND diets with psychological distress. Serum vitamin D, classified as sufficient, insufficient, deficient, or severely deficient, showed no significant association with psychological symptoms in crude or adjusted analyses.</p> Conclusion <p>Adherence to healthy dietary patterns was associated to lower odds of depressive and anxiety symptoms. No significant link was found for vitamin D. Causality cannot be inferred due to the cross-sectional design.</p>