Treatment of nonvital immature permanent teeth with calcium hydroxide is associated with few difficulties such as weakened tooth root, root canal reinfection, and long treatment time. Mineral trioxide aggregate (MTA) apical plug method is an alternative treatment method for open apices and has gained popularity in the recent times. This case report describes the management of a late-referral case of periapically involved, traumatized immature permanent incisor by endodontic treatment and the use of MTA apical plug. After preparing the access cavity, the working length was determined. The root canals were irrigated with 3% sodium hypochlorite and disinfected with metapex for 2 weeks. MTA was then placed in the apical 3 mm of the root canal. The remaining part of the root canal was filled with thermoplastic gutta-percha, and the coronal restoration was finished with composite resin. After 1-year follow-up, radiograph showed successful healing of periradicular radiolucency.