BackgroundIntrahepatic cholangiocarcinoma (ICC) is an aggressive malignancy. We sought to examine the association between preoperative prognostic nutritional index (PNI) and long‐term overall survival among patients with ICC who underwent curative‐intent resection.MethodsPatients who underwent hepatectomy for ICC between 1990 and 2015 were identified using an international multi‐institutional database. Clinic‐pathological characteristics and long‐term outcomes of patients with PNI ≥ 40 and <40 were compared using univariable and multivariable analyses.ResultsAmong 637 patients, 53 patients had PNI < 40 (8.3%) and 584 patients had PNI ≥ 40 (91.7%). While there was no difference between PNI groups with regard to tumor size (P = .87), patients with PNI < 40 were more likely to have multifocal disease (PNI < 40, n = 16, 30.2% vs PNI ≥ 40, n = 65, 11.1%; P < 0.001), poorly differentiated or undifferentiated ICC (PNI < 40, n = 13, 25.5% vs PNI ≥ 40, n = 75, 13.1%; P = 0.020) and T2/T3/T4 disease vs patients with PNI ≥ 40 (PNI < 40, n = 38, 71.7% vs PNI ≥ 40, n = 265, 45.4%; P < 0.001). Patients with PNI ≥ 40 had better OS vs patients with PNI < 40 (5‐year OS: PNI ≥ 40: 47.5%, 95% CI, 42.2 to 52.6% vs PNI < 40: 24.6%, 95% CI, 12.1 to 39.6%; P < 0.001). On multivariable analysis, PNI < 40 remained associated with increase risk of death (HR, 1.71; 95% CI, 1.15 to 2.53; P = 0.008).ConclusionA low preoperative PNI was associated with a more aggressive ICC phenotype. After controlling for these factors, PNI remained independently associated with a markedly worse prognosis.