Metastatic small bowel cancers are extremely rare in clinical practice. Primary appendiceal adenocarcinoma with gastrointestinal metastasis is seldom reported in the literature. Here, we describe the case of an 80-year-old male patient with primary appendiceal adenocarcinoma, who presented to China Medical University Hospital with mid-gastrointestinal tract bleeding. Capsule endoscopy revealed stenotic bowel lumen, but the capsule was retained in the distal duodenum. Double-balloon enteroscopy demonstrated erosive and erythematous mucosa in the region of capsule retention. The retained capsule was retrieved successfully by using an electrosurgical snare. Histological examination and immunohistochemical staining of the biopsy specimen from the duodenal lesion strongly supported the diagnosis of metastatic appendiceal adenocarcinoma.