Adrenocortical carcinoma (ACC) is a rare malignant tumour from the adrenal cortex. Half of the cases are functional, with ACTH-independent autonomous cortisol production being the most common. It is rare for ACC to present with markedly elevated metanephrine levels, characteristic of pheochromocytoma. We report a case of a large functioning adrenal tumour with overlapping biochemical features of ACC and pheochromocytoma. Biopsy confirmed the histopathological diagnosis of metastatic ACC.