A 2-month-old infant presented with an enlarging scalp hemangioma and consumptive coagulopathy. The patient became severely thrombocytopenic despite medical treatment. Transarterial embolization with Onyx was performed with significant reduction in the size of the tumor and complete resolution of the thrombocytopenia within 12 hours. Onyx embolization appears to be an excellent treatment option for hemangiomas presenting with Kasabach-Merritt syndrome that are unresponsive to standard medical therapy.