Carcinosarcoma of gallbladder (CSGB) is a rare malignancy characterized by malignant epithelial and mesenchymal components. Its pathogenesis is unknown and most CSGBs are associated with poor survival because the disease normally presents at an advanced stage, and as a result, curative resection is uncommon. This report describes a case that underwent curative resection. A 77-year-old woman presented with right upper quadrant pain. The preoperative diagnosis was gallbladder (GB) cancer, and thus, curative radical cholecystectomy was performed. However, pathologic examination of the surgical specimen revealed that the tumor was composed of two histologic components of squamous cell carcinoma and spindle cell sarcoma, which was consistent with a diagnosis of carcinosarcoma. The tumor was found to extend to the perimuscular connective tissue and to have metastasized to one lymph node (LN). The prognosis of CSGB remains poor despite curative resection, and thus, the authors recommend that effort be made to improve surgical outcomes.