Craniopharyngiomas exhibiting histologic malignancy are extremely rare. Herein, we report the case of a 26-year-old male patient who underwent suprasellar mass excision via an interhemispheric transcallosal approach. Histopathological examination indicated that the craniopharyngioma was of the adamantinomatous subtype. The patient received postoperative medical treatment for endocrine dysfunction and diabetes mellitus without radiation treatment. Two years after the operation, he presented with progressive visual disturbance and altered mentality. Magnetic resonance imaging revealed a huge mass in the suprasellar cistern and third ventricle. He underwent a second operation via the same approach. The histopathological examination showed an adamantinomatous craniopharyngioma with sheets of solid proliferation in a spindled pattern, indicating malignant transformation. Malignant transformation of craniopharyngioma in the absence of radiation therapy has been reported in only five cases, including this one. We present a case of malignant transformation of craniopharyngioma with a brief review of relevant literature.