Expression of E-cadherin and β-catenin has been widely studied in various human and canine epithelial tumors and has been correlated with dedifferentiation, invasiveness, and metastasis. Choroid plexus tumors (CPTs) are of epithelial origin, and the most important prognostic factor in human medicine is the tumor grade. Limited information is available regarding E-cadherin and β-catenin expression in human CPTs, and no information is found in the veterinary literature. In the current study, 42 canine CPTs (19 choroid plexus papillomas and 23 choroid plexus carcinomas) were retrospectively reviewed, and the intensity and cellular staining pattern of E-cadherin and β-catenin were correlated with histological features, paying special attention to grade, invasion, and metastasis. In addition, cytokeratin and glial fibrillary acidic protein (GFAP) antibodies were evaluated as markers for canine CPTs. It was found that loss of E-cadherin and β-catenin expression was uncommon in canine CPTs. Rather, membranous expression of both molecules was increased in CPTs compared to normal choroid plexus (NCP), regardless of tumor grade. Additionally, aberrant cytoplasmic or nuclear expression of both E-cadherin and β-catenin was often observed in CPTs. GFAP was frequently expressed in CPTs in contrast to NCP. None of these parameters were correlated with malignancy, and therefore, do not appear to be useful for prognostic information. Nevertheless, a panel of antibodies including E-cadherin and GFAP might be useful to support the diagnosis of CPTs and help to differentiate them from other tumors, such as ependymomas and metastatic epithelial tumors.