Malignant extrarenal rhabdoid tumors (MERT) are aggressive malignancies of infancy with dismal prognosis; cardiac localization is extremely rare. A 5-month-old male was diagnosed with a cardiac MERT after finding a large heterogenous mass attached to the left ventricular wall. He responded well to initial intensive chemotherapy but developed tumor progression 4 months after diagnosis. Palliative treatment with ipilimumab and nivolumab was administered; however, he died within one week. New treatment options are essential to improve survival in patients where complete tumor resection is unattainable.