Although uncommon, ovarian cancer cells may spread to the rectal lymph nodes. However, few reports have described how to detect and treat such metastases. We report a case of a 59-year-old woman with mesorectal and pararectal lymph node metastases in recurrent ovarian carcinoma, detected conclusively using 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT), and treated by low anterior resection with total mesorectal excision aiming for macroscopic complete resection. The treatment goals for the patient were gradually changed from curative to palliative chemotherapy; she survived for 45 months without rectal obstruction after secondary debulking surgery, and was followed up until autopsy. Thus, 18F-FDG PET/CT may be valuable for detecting rectal lymph node metastasis and can play an essential role in planning treatment for recurrent ovarian carcinoma.