A Killian-Jamieson diverticulum (K3D) is an unfamiliar and rare cervical esophageal diverticulum. This diverticulum originates on the anterolateral wall of the proximal cervical esophagus through a muscular gap (the Killian-Jamieson space) below the cricopharyngeal muscle and lateral to the longitudinal muscle of the esophagus. To dale, only surgical treatment has been recommended for a symptomatic KJD due to its close proximity to the recurrent laryngeal nerve and the concern of possible nerve injury. Recently, traditional open surgery for a symptomatic KJD is being challenged by the development of new endoscopic techniques and devices. We present here a case of a symptomatic KJD that was successfully treated with the flexible endoscopic diverticulotomy using two new devices. An isolated-tip needle-knife papillotome (Iso-Tome) was used for the dissection of the tissue bridge of the diverticulum. And a flexible overtube with a modified distal end (a tilted overtube) was used for adequate visualization of the tissue bridge of the diverticulum and protection of the surrounding tissue during dissection of the tissue bridge. Our successful experience suggests that the flexible endoscopic diverticulotomy with the use of appropriate endoscopic devices can be a safe and effective method for the treatrnent of a symptomatic KJD.