Marsupialization, a common conservative management of intra-oral cystic lesion, is also applied to some benign tumors. However, there is limited research on the use of marsupialization as a treatment for adenomatoid odontogenic tumors. This case report focuses on an 18-year-old male patient who was diagnosed with an adenomatoid odontogenic tumor in the right lower mandible following an incisional biopsy. Within six months of follow-up at the outpatient department after marsupialization, a decrease in tumor size and separation from the inferior alveolar nerve were observed. Cystic enucleation and curettage were performed nine months after marsupialization, and the capsule was found to be thickened. The tumor was successfully removed in its entirety. After the surgery, the patient continued to be followed up at our outpatient department. The surgical wound healed well, and new bone formation was observed. There was no evidence of recurrence. This case report showed marsupialization could be one of the conservative managements of mandibular adenomatoid odontogenic tumor with a promising outcome. However, further research and more cases are needed to establish the effectiveness of marsupialization for the treatment of adenomatoid odontogenic tumors.