Vascular tumors in neonates are mostly benign; however, locally aggressive voluminous forms may destabilize the hemodynamics of a neonate. Herein, we present an unusual case of a neonatal giant vascular tumor in the right upper extremity, causing a consumption coagulopathy and acute deterioration of vital signs. The patient required mechanical ventilation, inotropic support, and administration of blood products by the seventh day. Vascular embolization attempts failed to improve the general condition of the patient. Due to the deteriorating and life-threatening general condition of the patient, amputation around the upper arm level occurred under emergency conditions on the twelfth day. The patient’s hemodynamic parameters were regained immediately, with neither inotropic agents nor blood products required after the second postoperative day. Clinical and pathological diagnosis revealed kaposiform hemangioendothelioma. Patient monitoring proceeded until the age of 15 months, with no local recurrence around the stump or soft tissue coverage complications. Therefore, since other treatment options failed, the early amputation decision was life-saving.