Objective: Patients with autoimmune disease may have impaired cancer survival. The aim was to investigate the association between autoimmune disease and ovarian cancer survival. Methods: From the Extreme study, we included women diagnosed with epithelial ovarian cancer (EOC) in Denmark during 1990–2014 (n = 11,870). Information on exposure and covariates was retrieved from nationwide registries. Using pseudo-values, we estimated absolute and relative 5- and 10-year survival probabilities with 95% confidence intervals (CIs) for autoimmune diseases combined and for the four most common individual disorders in our study population, namely type 1 diabetes, rheumatoid arthritis, Graves' disease, and inflammatory bowel disease. Results: The overall 5- and 10-year absolute survival probabilities were 35% and 24%, respectively, in women with EOC without autoimmune disease. Autoimmune diseases combined was not significantly associated with survival among women with EOC (5-year adjusted relative survival probability = 1.01, 95% CI: 0.94–1.09; 10-year adjusted relative survival probability = 0.90, 95% CI: 0.81–1.00). However, stratification by disease stage showed an impaired 10-year survival in women with autoimmune disease and a localized EOC (relative survival probability = 0.86, 95% CI: 0.76–0.97). None of the individual autoimmune diseases were statistically significantly associated with EOC survival. Conclusions: Only among women with localized EOC, there seemed to be a long-term survival loss associated with a history of autoimmune disease. In contrast, no significant association between a history of autoimmune disease and survival was observed in women with nonlocalized EOC where the survival is already low.