Approximately 5% to 15% cases of endogenous Cushing syndrome are due to ectopic adrenocorticotrophic hormone (ACTH)-producing neuroendocrine tumors, which are commonly located in bronchopulmonary system, thymus, and gastrointestinal tract including pancreas. Although carcinoid tumors of the appendix are revealed in 0.3% of patients undergoing routine appendectomy, ACTH-secreting appendicular carcinoid is a rare entity. We present a case of a 22-year-old woman with ectopic ACTH-dependent Cushing syndrome due to an appendicular carcinoid, which was localized with the help of Ga-DOTATATE PET/CT scan.