Pheochromocytoma is a rare tumor originating from the embryonic neural crest and secreting high levels of catecholamines. The average tumor size is approximately 7 cm, and the average weight is approximately 200 g in the previous publications. Sometimes these tumors may be bigger. In this report, a case of multicystic malignant pheochromocytoma with a huge size is presented, which is seldom reported in the past. A 37-year-old male patient was referred to our hospital for etiological investigation of his recently diagnosed hypertension. Contrast-enhanced computed tomography (CT) examination was performed for further evaluation of the lesion and surrounding tissues. The lesion was 18x8x13 cm in size. It had lobulated margins, large cystic components, and peripheral and septal contrast enhancement. The levels of metanephrine, normetanephrine, adrenaline, noradrenaline, vanilmandelic acid, and dopamine were significantly elevated. The patient was prepared for surgery. In the pathological evaluation, the mass weighed 1018 g and was 18x8x13 cm in size. He was diagnosed with malignant pheochromocytoma. After eight months, a CT examination showed a recurrent mass, liver metastasis, and distant metastasis. The patient received chemotherapy and radiotherapy. Multicystic malignant pheochromocytoma may reach huge sizes without causing any symptoms.