Objective To determine the expression of signal transducers and activators of transcription 3 (STAT3) in intrahepatic cholangiocarcinoma (ICC) and to evaluate its influence on the outcome and prognosis of patients. Methods The expression of STAT3 was examined in intrahepatic cholangiocarcinoma (ICC) by immunohistochemistry assays. The correlation between STAT3 expression and clinicopathological parameters was analyzed by Pearson χ² test and Fisher's exact test. Kaplan-Meier (KM) method was used to estimate and draw the survival curves, and the log-rank test was employed to compare the survival curves between groups. The effects of clinicopathological parameters and STAT3 expression on survival rate of patients were analyzed by Cox regression model. Results The expression of STAT3 in ICC tumor tissues was higher than that in peritumoral tissues, and was closely correlated with the tumor size, pathological satellite, microvascular invasion, undifferentiated-type histology and lymph node metastasis. Patients with high STAT3 expression had a poor prognosis with respect to overall survival (OS) and disease-free survival (DFS). The Cox multivariate survival analysis indicated that STAT3 was an independent prognostic factor for OS. Conclusion High STAT3 expression in ICC is correlated with worse surgical outcomes and it is an independent factor of prognosis, and may also serve as a potential target for treatment of ICC.