Purpose This study evaluated the prognostic value of C-reactive protein-to-albumin (CAR) and neutrophil-to-lymphocyte ratios (NLR) in conjunction with host-related factors in patients with unresectable advanced or recurrent gastric cancer. Methods A total of 411 patients with unresectable advanced gastric cancer were treated at Kochi Medical School between 2007 and 2019. Associations between clinicopathological parameters and systemic inflammatory and nutritional markers, including CAR and NLR, with overall survival were analyzed retrospectively. Results The optimal cut-off values of predicted median survival time were 0.096 (sensitivity, 74.9%; specificity, 42.5%) for CAR and 3.47 (sensitivity, 64.1%; specificity, 57.5%) for NLR, based on the results of receiver operating characteristic analysis. A weak significant positive correlation was identified between CAR and NLR (r = 0.388, P < 0.001). The median survival time was significantly higher in patients with intestinal-type than those with diffuse-type histology (18.3 months vs. 9.5 months; P = 0.001), CAR < 0.096 than those with CAR >= 0.096 (14.8 months vs. 9.9 months; P < 0.029), and those with NLR < 3.47 than NLR >= 3.47 (14.7 months vs. 8.8 months; P < 0.001). Multivariate survival analysis revealed that diffuse-type histology (hazard ratio (HR) 1.865; 95% confidence interval (CI) 1.397-2.490; P < 0.001)), 1 or more performance status (HR 11.510; 95% CI 7.941-16.683; P < 0.001), and NLR >= 3.47 (HR 1.341; 95% CI 1.174-1.769; P = 0.023) were significantly associated with independent predictors of worse prognosis. Conclusions High CAR and NLR are associated with poor survival in patients with unresectable and recurrent gastric cancer.