The prognosis of patients with intrahepatic cholangiocarcinoma (ICC) is extremely poor and the recurrence rate after curative operation is very high. There is no standard treatment to prevent recurrence of ICC. In this study, we investigated the clinical utilization of a dendritic cell vaccine plus activated T-cell transfer in an adjuvant setting for postoperative ICC. 36 patients with ICC were vaccinated at least 3 times with autologous tumor lysate pulsed dendritic cells plus ex-vivo activated T-cell transfer. The 5-year progression-free survival (PFS) and overall survival (OS) were measured and compared with those of 26 patients who received the curative operation alone as a concurrent control. The registration number was UMIN000005820. The median PFS and OS were 18.3 and 31.9 months in the patients receiving adjuvant immunotherapy and 7.7 and 17.4 months in the group receiving surgery alone (p = 0.005 and 0.022, respectively). In the treated group, patients whose skin reactions were 3 cm or more at the vaccine site showed dramatically better prognosis (PFS p < 0.001, OS p = 0.001). A postoperative dendritic cell vaccine plus activated T-cell transfer would be a feasible and effective treatment for preventing recurrence and achieving long-term survival in ICC patients.