<b>Background:</b> Diet quality has been associated with lower risk of respiratory diseases, but evidence from studies representative of the US population is limited. <b>Objective:</b> To investigate the association of ventilatory function and diet quality in adults participating in the National Health and Nutrition Examination Survey (NHANES) <b>Methods:</b> Analyses included US adults aged 19-70 years old who completed at least one 24-hour dietary recall and underwent pre-bronchodilator spirometry (forced expiratory volume in 1 second [FEV₁], forced vital capacity [FVC], and FEV₁/FVC) in three NHANES cycle years (2007-2012). Only individuals whose spirometry met ATS quality standards, and who had plausible dietary intake were included (n=10,428). The Alternative Healthy Eating Index (AHEI) score was used to ascertain diet quality (range 0-110, higher=better diet quality). Weighted linear regression models were used to examine the association of ventilatory function outcomes and AHEI-score, adjusting for age, sex, height, race, income, body mass index, education, smoking status, and physical activity. <b>Results:</b> Participants had a mean AHEI-score of 44.60 (SD± 12.82), indicating low diet quality. A per-standard deviation increase in AHEI-score was statistically significantly associated with a greater FVC [mL] (adjusted [a] b-coefficient 26.82; 95% confidence interval [CI] 11.65, 42.00; p-value &lt;0.001), and FEV₁ [mL] ([a]b-coefficient 20.39 (CI 4.86, 35.92; p-value=0.01)) but not with FEV₁/FVC ([a]b-coefficient 0.02 (95% CI -0.20, 0.23). <b>Conclusion:</b> This large population-based study showed that better quality diet was associated with improved lung function in US adults.