Anal canal adenocarcinoma is a relatively rare malignancy without established diagnostic and treatment criteria. Case reports of chemotherapy for anal canal adenocarcinoma with distant metastasis are limited, and there is no convincing evidence for treatment effectiveness. A 62-year-old man complained of difficulty in defecation, anal pain, and bleeding during bowel movement. He was diagnosed with moderately differentiated primary anal canal adenocarcinoma. A computed tomography scan revealed multiple metastases in the lung and liver. The patient was treated with abdominoperineal resection to control local tumor growth and then with chemotherapy consisting of mFOLFOX6 + bevacizumab. Because he had an activating KRAS mutation, anti-EGFR therapy was not considered. A reduction in the size of lung and liver metastases was observed after 4 courses of mFOLFOX6 + bevacizumab, and after 22 courses, maximum reduction in the metastatic lesions was achieved. The patient demonstrated tolerable levels of oxaliplatin-related peripheral neurotoxicity (grades 1-2) and was considered as having partial response to treatment. He is currently at the partial response state for 1 year. We plan to continue the treatment unless the patient develops progressive disease or intolerable adverse reactions. This case demonstrates that anal canal adenocarcinoma with distant metastases could be successfully treated with mFOLFOX6 + bevacizumab therapy according to the guidelines for rectal carcinoma. However, as anal canal carcinoma has multiple histological subtypes, it is important to establish subtype-specific treatment strategies.