Adequate management of hyperleukocytosis in patients with acute myeloid leukemia (AML) is essential for the prevention of life-threatening complications related to leukostasis and tumor lysis syndrome, but the optimal therapeutic strategy remains unclear. We report a 15-year-old girl with newly diagnosed AML who had extreme hyperleukocytosis (leukocyte count at diagnosis, 733,000/μl) leading to a brain hemorrhage. She was initially treated with hydroxyurea, but presented with brain hemorrhage due to leukostasis and underwent leukapheresis emergently with intensive care and mechanical ventilation. Full-dose standard induction chemotherapy was initiated after achieving gradual cytoreduction (leukocyte count, 465,000/μl) within five days after the initiation of therapy with hydroxyurea and leukapheresis. These treatments were successful and she experienced no complications. The patient ultimately recovered fully and was discharged with complete remission of AML. Although the effects of hydroxyurea and leukapheresis in the setting of hyperleukocytosis are still controversial, these initial treatments may contribute to successful bridging therapy followed by subsequent induction chemotherapy, especially in AML cases with extreme hyperleukocytosis or life-threatening leukostasis.