Background: Thymic Neuroendocrine Tumor (TNET) is a rare clinical condition with approximate incidence rate of 2–5%. Carcinoid tumor of thymus with Cushing’s syndrome (CS) is also a rare co-morbid condition. Case information: Here we report a case of a 22-year-old gentleman presented with uncommon features suggestive of CS. He was evaluated and diagnosed with ectopic Adrenocorticotropic hormone (ACTH)–dependent CS due to a TNET. Results: Extensive thymectomy was performed and histopathology confirmed the diagnosis of thymic carcinoma with neuroendocrine differentiation and local and pericardial invasion. Conclusion: Thymic carcinomas may present with symptoms due to mass effect but Cushing syndrome is the most common endocrine manifestation of these tumors. Surgery is the most effective treatment of thymic carcinoma, although chemotherapy and radiotherapy also have been reported to be effective in some cases.