Advanced-stage epithelial ovarian cancer is associated with variable survival outcomes, despite standardized treatments. Identifying reliable and accessible prognostic markers is critical to guide clinical decision-making. : The aim of this study was to evaluate the prognostic significance of the modified Glasgow Prognostic Score (mGPS) in patients with FIGO stage III-IV epithelial ovarian cancer. : In this retrospective cohort study, 89 patients diagnosed between 2018 and 2023 were analyzed. The mGPS was calculated from pre-treatment serum C-reactive protein (CRP) and albumin levels. Overall survival (OS) was assessed using Kaplan-Meier and Cox regression analyses. : The median OS was 32.3 months. When stratified by mGPS categories, the 2-year survival rates were 94%, 75%, and 34% in the mGPS 0, 1, and 2 groups, respectively ( < 0.001). In the multivariate Cox proportional hazards model, both mGPS (HR = 1.85; 95% CI: 1.12-3.07; = 0.016) and ECOG performance status (HR = 1.67; 95% CI: 1.02-2.75; = 0.043) were identified as independent predictors of overall survival. : The mGPS is a simple, low-cost, and independently predictive tool for overall survival in advanced ovarian cancer. By capturing both systemic inflammation and nutritional status, it enhances risk stratification and may support individualized treatment planning. Prospective validation is warranted.