Background: In the present study, we explored the association between major dietary patterns, odds, and severity of anxiety disorders, which has not been clarified to date. Methods: This case-control study was conducted on 85 patients who were group-matched by gender with 170 healthy subjects. Dietary intakes were evaluated applying a 147-item validated food frequency questionnaire (FFQ). Anthropometric data collection was accomplished based on precise clinical assessments. Major dietary patterns were identified using principal component analysis (PCA). Multivariate odds ratios (OR) with 95% confidence intervals (CI) were used to investigate the association of the identified dietary patterns with anxiety disorders. Multiple linear regression analysis was used to evaluate the association between the GAD-7 score and major dietary pattern scores. Results: Three major dietary patterns were derived through PCA labeled as 'healthy', 'Western', and 'Mixed'. Those in the top tertile of the healthy dietary pattern were less likely to have anxiety disorders (OR = 0.26; 95%CI: 0.10, 0.66), while no significant relationship was found between Western and mixed dietary patterns and the odds of anxiety disorders. The severity of anxiety disorders, assessed by the GAD-7 score, was reduced by higher adherence to healthy dietary pattern ( P = 0.003), and increased by greater adherence to mixed ( P = 0.002) and Western ( P = 0.001) dietary patterns. Conclusion: We provided evidence demonstrating an inverse association of healthy dietary pattern with odds, and severity of anxiety disorders. Also, higher adherence to Western and mixed dietary patterns resulted in greater GAD-7 scores.