Abstract: Pheochromocytoma (PCC) co-existing with ectopic adrenocorticotropic hormone (ACTH) syndrome (EAS) represents a rare endocrine emergency. Cases presenting clinically with abdominal pain and intestinal perforation are exceedingly rare. Such patients may lack typical symptoms of Cushing’s syndrome (CS) or PCC, posing a high risk of misdiagnosis. Caution is required in performing the high-dose dexamethasone suppression test (HDDST) for functional diagnosis to avoid precipitating a pheochromocytoma crisis. This report presents the case of a 67-year-old man with recent blood pressure fluctuations and a long-standing history of chronic abdominal distension and constipation. Laboratory investigations revealed severe hypokalemic alkalosis, markedly elevated plasma cortisol and ACTH levels with non-suppression on the low-dose dexamethasone suppression test, and significantly elevated plasma metanephrines (MNs). Contrast-enhanced adrenal CT demonstrated a left adrenal mass (41 mm × 38 mm × 42 mm). ⁶⁸Ga-DOTATATE positron emission tomography (PET)-CT showed intense radiotracer uptake in the same nodule. Surgery remains the cornerstone of treatment. Preoperative management with cortisol synthesis inhibitors is recommended to rapidly control hypercortisolism, allowing for safer and earlier surgical intervention.