BACKGROUND: Preserved Ratio Impaired Spirometry (PRISm) is increasingly recognized as a precursor to Chronic Obstructive Pulmonary Disease (COPD). The impact of Ultra-Processed Foods (UPFs) intake on PRISm and lung function remains underexplored, and we aimed to explore their associations. METHODS: This study included 8,336 U.S. adults. Weighted logistic and linear regression models were employed for main analysis. Dose-response relationship was examined through restricted cubic spline (RCS) analysis, and subgroup analyses explored interactions with selected covariates. RESULTS: Participants in the PRISm group were older and exhibited various adverse health characteristics. The percentage of total daily energy intake from UPFs (%Kcal) intake was associated with a non-significant increase in PRISm risk (OR 1.67, 95% CI: 0.96-2.92, CONCLUSION: Higher intake of UPFs is linked to an increased risk of PRISm and negatively affects lung function, particularly in individuals with occupational exposure.