This case report demonstrates the feasibility of performing a complete resection of the odontoid via an entirely transnasal and fully endoscopic approach. A 40-year-old male patient with a previous diagnosis of type I Arnold-Chiari malformation had a posterior dislocation of the odontoid process that caused severe anterior compression of the brainstem. Type I Arnold-Chiari malformation consists of a congenital malformation of the posterior cranial fossa causing herniation of the cerebellum and brainstem through the foramen magnum into the spinal canal. In the presence of ventral brainstem compression, the most widely used anterior approach to the cervicomedullary junction via the atlantoaxial region is a transoral route. This report attempts to demonstrate that an endoscopic endonasal approach should now be considered an excellent alternative to the traditional transoral approach in selected cases.