Purpose The C-reactive protein (CRP)/albumin ratio has been identified as a potential prognostic factor for several malignancies. We, therefore, assessed the prognostic role of the CRP/albumin ratio in resected extrahepatic cholangiocarcinoma (EC). Materials and methods A total of 235 patients were retrospectively analyzed between March 2005 and December 2017. The correlations among the preoperative CRP/albumin ratio, clinicopathological factors, and clinical outcomes were investigated. Results There were 143 males (60.8%), and the median age at the diagnosis was 70.1 (range 41.0–85.5) years. Patients were diagnosed with perihilar bile duct cancer ( n  = 61) and distal bile duct cancer ( n  = 174). The median recurrence-free survival and overall survival were 32.7 and 38.7 months, respectively. The optimal prognostic cut-off point of the CRP/albumin ratio for the survival was 0.18 (× 10 3 ). According to the Kaplan–Meier analysis with a log-rank test, the high CRP/albumin ratio group (≥ 0.18) had a significantly shorter overall survival than the low CRP/albumin ratio group (< 0.18) (29.8 vs. 54.6 months, p  = 0.002). A multivariate logistic regression analysis for the overall survival showed that CA19-9 ≥ 37 and a high CRP/albumin ratio were associated with a shorter overall survival. Conclusion A high CRP/albumin ratio appears to be significantly associated with clinically worse outcomes in patients with resected EC.