Background: Hepatitis B core antibody (HBcAb) positivity is considered a prior hepatitis B virus (HBV) infection. However, little is known about the effect of HBcAb positivity on surgical safety for hilar cholangiocarcinoma (hCCA). The present study aims to investigate the role of HBcAb positivity on postoperative complications of hCCA.Methods: A retrospective analysis was performed on the status of HBcAb positivity, liver fibrosis, perioperative surgical complications, and long-term outcomes of hCCA patients with Hepatitis B surface antigen (HBsAg) negativity who underwent surgical treatment in Tongji Hospital from April 2012 to September 2019.Results: HBcAb positivity with negative HBsAg occurs in 137 hCCA patients (63.1%). A total of 99 hCCA patients with negative HBsAg underwent extended hemihepatectomy, of whom 69 (69.7%) and 30 (30.3%) were HBcAb-positive and HBcAb-negative, respectively. Significant fibrosis was detected in 63.8% of the patients with HBcAb-positive, which was markedly higher than those with HBcAb-negative (36.7%) (p = 0.016). The postoperative complications and 90-day mortality rates were 37.4% (37/99) and 8.1% (8/99), respectively. The incidence of postoperative complications in HBcAb-positive patients (44.9%) was significantly higher than that in HBcAb-negative patients (20.0%) (p = 0.018). All the patients who died within 30-day after surgery were HBcAb-positive. Multivariate analysis showed that the independent risk factors for complications were HBcAb positivity, preoperative cholangitis, portal occlusion > 15 min, and significant fibrosis. There were no significant differences in recurrence-free survival (RFS) and overall survival (OS) between HBcAb-positive and HBcAb-negative patients (p = 0.642 and p = 0.400, respectively).Conclusions: HBcAb positivity is a common phenomenon in hCCA patients from China, a country with highly prevalent HBcAb positivity. The status of HBcAb-positive markedly increases the incidence of postoperative complications after extended hemihepatectomy for hCCA patients.