Liver Cirrhosis, defined as the final stage of chronic liver disease, may become more prevalent in the lower level of body defense against oxidation and inflammation. Therefore, we assessed the association of dietary total antioxidant capacity (DTAC) with the severity and mortality of cirrhosis in a cohort study. 120 newly diagnosed cirrhosis patients from Tehran, Iran, participated in this study. The patients’ habitual diet was assessed using a 168-item validated food frequency questionnaire. Both ferric-reducing antioxidant potential (FRAP) and oxygen radical scavenging capacity (ORAC) methods were computed to achieve DTAC scores. The association between DTAC with disease severity and mortality was estimated by multivariate linear regression and cox proportional hazards regression models. Dietary total antioxidant capacity-ORAC had a significant inverse association with disease severity in both crude and adjusted models (P for trend: <0.001 and 0.016 respectively). The risk of mortality in the first and second tertiles of ORAC was 5.56 (95 % CI: 2.25–13.75; P = 0.002) and 3.20 (95 % CI: 1.25–8.19; P = 0.015) higher than those in the third category, respectively. In conclusion, a higher antioxidant capacity of diet is associated with less disease severity and mortality risk in cirrhosis.