Adenocarcinoma arising from heterotopic gastric mucosa (HGM) is exceedingly rare. This report presents the case of a 57-year-old male who presented with the chief complaint of dysphagia. Endoscopy and computed tomography revealed a locally advanced tumor of the cervical esophagus and swollen mediastinal lymph nodes. He underwent chemoradiotherapy followed by esophagectomy with three-field lymph node dissection. The resected tumor was a circumferentially scarred lesion located 1.5 cm from the proximal margin. The tumor was identified to be a well-differentiated adenocarcinoma arising from HGM with invasion to the muscularis propria. Postoperative chemoradiotherapy was performed because positive surgical margins were observed in the resected tissue. The patient has remained alive for more than 4 years after surgery, without any evidence of recurrence.