We report successful radical systematic surgery for an undifferentiated gallbladder carcinoma with metastasis to the mesocolonic lymph nodes. The patient, a 70-year-old woman, was admitted with abdominal fullness and appetite loss. Imaging modalities revealed a 10-cm tumor originating from the gallbladder and infiltrating both the liver and transverse colon. As multiple mesocolonic lymph node metastasis was confirmed on laparotomy, right hemicolectomy with systematic lymph node dissection (D3 resection) was performed, in addition to extended cholecystectomy with partial resection of segments 4, 5 and 6 of the liver and distal gastrectomy. Histologically, the tumor was diagnosed as an undifferentiated carcinoma, and metastases were indentified in the mesocolonic lymph nodes (17/50 nodes) but not in the peri-gallbladder lymph nodes (0/16 nodes). The patient has been recurrence-free for 4 years after the operation. This case illustrates that even if gallbladder cancer infiltrates into adjacent organs with regional lymph node metastasis, it is of value to perform radical surgery with systematic lymph node dissection for the involved organs.