Adrenocortical carcinoma (ACC) is a rare and aggressive neoplasm with poor prognosis. We report a case of a 30-year-old female who presented with profound classic features of an adrenocorticotrophic hormone (ACTH)-independent Cushing's syndrome (CS) and a large adrenal mass with massive venous tumor thrombosis of the entire inferior vena cava (IVC), left renal and adrenal veins confirmed by imaging. Adrenal biopsy histopathology and immunohistochemistry confirmed ACC. Systemic palliative chemotherapy was administered. This rare case presents a unique and atypical presentation of an extensive tumor thrombosis of IVC. With the advanced stage at diagnosis, aggressive nature and poor prognosis of the disease, there is still a need to determine viable therapeutic options for metastatic ACC associated with venous invasion.