Pheochromocytoma is a rare cause of ectopic Cushing's syndrome and presents a challenge to the clinician in the diagnosis and treatment. In this study, a rare case of adrenocorticotropic hormone-producing pheochromocytoma is presented. A 55-years-old man with the symptoms of hypercortisolism, multidrug-resistant hypertension, and an adrenal mass is presented. The laboratory results were consistent with hypercortisolism, high plasma adrenocorticotropic hormone, high 24-hour urine metanephrine and normetanephrine and severe hypokalemia. Abdominal computerized tomography showed a 3-cm non-adenoma left adrenal mass. After preoperative management, left adrenalectomy was performed. A histopathological examination revealed a 2.5 cm pheochromocytoma with focal positivity for adrenocorticotropic hormone. The patient was discharged with full recovery under hydrocortisone replacement therapy. Furthermore, six weeks after the operation, 24-hour urinary excretion of metanephrine and normetanephrine was within normal ranges. In conclusion, an adrenocorticotropic hormone-producing pheochromocytoma should be considered in patients with clinical manifestations of ectopic Cushing's syndrome and adrenal mass.