Epithelioid angiosarcoma is an extremely rare subtype of cardiac angiosarcoma that is highly aggressive and associated with poor prognosis. Due to its rare nature, the epidemiology and pathogenesis of this disease are not well-known. Thus, effective diagnostic and treatment modalities are limited. Here, we report a case of a primary epithelioid angiosarcoma in a patient who was treated successfully with surgical resection. A 45-year-old woman who initially presented with chronic systemic symptoms and severe anemia and subsequently developed new-onset atrial fibrillation with rapid ventricular rate was found to have a right-sided cardiac mass with a large pericardial effusion. Several years prior to presentation, she was treated for localized papillary thyroid cancer with Gc protein-derived macrophage-activating factor (Gc-MAF) therapy after declining thyroidectomy. After initial workup of her cardiac mass, including a transthoracic echocardiogram and cardiac MRI, she was transferred to an outside hospital where her mass was surgically resected. She was found to have stage IIIA high-grade epithelioid angiosarcoma involving the inferior vena cava, right atrium, and pericardium. She subsequently had complete resolution of her pericardial effusion and anemia and continues to have good performance status 16 months after her excellent surgical outcome without evidence of recurrence. This unique case contributes to our knowledge of epithelioid cardiac angiosarcoma, of which limited number of cases has been reported. It highlights a favorable outcome following surgical resection of a rare, life-threatening primary cardiac tumor.