Mycotic aneurysms (MAs) are a rare but life-threatening complication of infective endocarditis (IE), resulting from septic emboli lodging in cerebral vessels and leading to aneurysm formation. This case report describes a 17-year-old female who developed multiple MAs during treatment for IE, resulting in catastrophic neurological decline and eventual death. After undergoing open-heart surgery for vegetation excision, our patient then developed intracranial bleeding due to mycotic aneurysms rupture, which led to her death after an unsuccessful decompressive craniotomy. This case highlights the importance of early recognition and timely intervention in the management of MAs in the context of IE, as well as the need for protocols to improve outcomes in these high-risk patients. The high mortality rate associated with ruptured MAs highlights the critical nature of these complications and the challenges in their management.