Leukapheresis is a treatment used to reduce leukocytes to decrease the number of white blood cells in circulation and prevent the risks of hyperviscosity and cerebrovascular and pulmonary leukostasis. We present a case of pro-B-cell acute lymphoblastic leukemia (ALL) with hyperleukocytosis in a 6-month-old infant, characterized by a positive KMT2A/AFF1 fusion gene with a leukocyte count of 1,755 × 10/L. After two consecutive sessions of leukapheresis, the white blood cell count decreased to 55 × 10/L. The infant recovered after the high-dose methotrexate chemotherapy. These results demonstrate that leukapheresis is a feasible treatment option for acute hyperleukocytic leukemia in infants with ALL.