Cholangiocarcinoma is a rare hepatic malignancy in domestic cats, and its etiology remains largely undefined. Domestic cat hepadnavirus (DCHBV), a recently discovered member of the _Orthohepadnavirus_ genus, shares similarities with human hepatitis B virus (HBV), which is associated with liver cancers, including cholangiocarcinoma. Here, we report a case of cholangiocarcinoma in a feline immunodeficiency virus-positive, 17-year-old spayed female cat infected with DCHBV. The patient presented with persistent vomiting, anorexia, and an elevated globulin level. Ultrasound revealed multiple hypoechoic hepatic lesions, and histopathology confirmed cholangiocarcinoma. Using quantitative PCR, DCHBV was detected in the spleen and ascitic fluid, and full-genome sequencing identified a unique 12-base deletion in both the polymerase and surface protein genes. Immunohistochemistry and RNA _in situ_ hybridization demonstrated DCHBV core protein and mRNA expression in both tumor and non-tumor liver tissues, though signals were more prominent in non-neoplastic hepatocytes. The tumor exhibited CK7 positivity and HepPar-1 negativity, confirming biliary origin. While the causal relationship between DCHBV and cholangiocarcinoma remains to be clarified, the presence of a viral antigen and mRNA in neoplastic tissue suggests a potential role for DCHBV in hepatobiliary carcinogenesis. This is the first report describing cholangiocarcinoma in a cat with DCHBV infection, raising the possibility that DCHBV may have broader pathogenic potential beyond hepatitis and hepatocellular carcinoma.