Unicysticameloblastoma is a rare, benign, locally invasive odontogenic neoplasm of young age that show clinical, radiographic, or gross features of an odontogenic cyst, but histologically shows typical ameloblastomatous epithelium lining part of the cyst cavity, with or without luminal and/or mural tumor growth. This case report describes the case of a 4-year-old boy with unicysticamelobastoma of the mandible, which involved unerupted left first premolar. Marsupialization with obturation placement was performed to shrink the lesion. Later enucleation was performed to remove all cystic lesion. Five months post-operative, the lesion had started healing. The combination of conservative surgery and obturator placement effectively lead to shrinkage of the lesion and preserved mandibular growth.