Background Although non-alcoholic fatty liver disease (NAFLD) is linked to infammation, whether an infammatory diet increases the risk of NAFLD is unclear. This study aimed to examine the association between the Energy-adjusted Diet Infammatory Index (E-DII) score and severe NAFLD using UK Biobank. Methods This prospective cohort study included 171,544 UK Biobank participants. The E-DII score was computed using 18 food parameters. Associations between the E-DII and incident severe NAFLD (defned as hospital admission or death) were frst investigated by E-DII categories (very/moderately anti-infammatory [E-DII< −1], neutral [E-DII−1 to 1] and very/moderately pro-infammatory [E-DII>1]) using Cox proportional hazard models. Nonlinear associa‑ tions were investigated using penalised cubic splines ftted into the Cox proportional hazard models. Analyses were adjusted for sociodemographic, lifestyle and health-related factors. Results Over a median follow-up of 10.2 years, 1489 participants developed severe NAFLD. After adjusting for confounders, individuals in the very/moderately pro-infammatory category had a higher risk (HR: 1.19 [95% CI: 1.03 to 1.38]) of incident severe NAFLD compared with those in the very/moderately anti-infammatory category. There was some evidence of nonlinearity between the E-DII score and severe NAFLD. Conclusions Pro-infammatory diets were associated with a higher risk of severe NAFLD independent of confound‑ ers such as the components of the metabolic syndrome. Considering there is no recommended treatment for the disease, our fndings suggest a potential means to lower the risk of NAFLD.