Objective To investigate the efficacy and safety of reduced-dose emicizumab (EMI) prophylaxis in infants under one year of age with severe hemophilia A (HA). Methods Medical records of 11 infants aged ≤12 months with severe HA who received reduced-dose EMI in the Department of Hematology and Oncology, Shenzhen Children's Hospital, from July 2022 to June 2025 were retrospectively reviewed. Efficacy and safety were analyzed statistically. Results The median age at EMI initiation was 7.9 months (range 4.2-11.2 months). The median loading dose (first 4 weeks) and median maintenance dose were 6.2 mg/kg per 4 weeks (range 2.8-12.6 mg/kg per 4 weeks) and 3.1 mg/kg per 4 weeks (range 2.0-4.8 mg/kg per 4 weeks), respectively. The median duration of EMI prophylaxis was 15.8 months (range 1.7-36.0 months). After treatment, the median (range) annualized bleeding rate, spontaneous annualized bleeding rate, and annualized treated bleeding rate were 0.5 (0-6.2), 0 (0-0.5), and 0 (0-3.0), respectively. All decreased compared with pre-treatment, and the reduction in spontaneous annualized bleeding rate was statistically significant (P<0.05). Overall, 64% (7/11) of patients experienced no bleeding events requiring treatment. No EMI-related adverse events were observed. Conclusions Reduced-dose EMI prophylaxis effectively controls bleeding in infants with hemophilia A and shows good safety.