Hepatocellular carcinoma (HCC) and chronic liver disease (CLD) are major sources of morbidity and mortality globally. Both HCC incidence and CLD mortality are known to vary by race. There is limited research on the association between dietary measures and these outcomes in a diverse population. We prospectively investigated the associations between four diet quality index (DQI) scores (Healthy Eating Index-2010, Alternative Healthy Eating Index-2010, Alternate Mediterranean Diet [aMED], and Dietary Approaches to Stop Hypertension), HCC incidence, and CLD mortality in the Multiethnic Cohort. We analyzed data from 169,806 African Americans, Native Hawaiians, Japanese Americans, Latinos, and whites, aged 45 to 75 years. DQI scores were calculated by using a validated food frequency questionnaire administered at baseline. During an average 17 years of follow-up, 603 incident cases of HCC and 753 CLD deaths were identified among study participants. Multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) for each DQI were estimated using Cox regression. Higher aMED scores, reflecting favorable adherence to a healthful diet, were associated with a lower risk of HCC (quintile [Q]5 versus Q1 HR, 0.68; 95% CI, 0.51-0.90; trend, P = 0.02). In racial/ethnic-specific analyses, there was no significant heterogeneity across groups (interaction, P = 0.32); however, the association only remained statistically significant among Latinos (Q4 versus Q1 HR, 0.47; 95% CI, 0.29-0.79; trend, P = 0.006). All DQI measures were inversely associated with CLD mortality, with no significant heterogeneity by race/ethnicity. Conclusion: Higher aMED scores were associated with a lower risk of HCC. A higher score of any DQI was associated with a lower risk of CLD mortality. These results suggest that better diet quality may reduce HCC incidence and CLD mortality.