Background and aim: Around 2% of newborns are at risk of hepatitis B virus (HBV) infection from their mothers. To prevent this, infants born to HBsAg-positive mothers are given hepatitis B immune globulin (HBIG) and hepatitis B (HB) vaccine as immunoprophylaxis. This study aims to investigate the efficacy of immunoprophylaxis in infants born to HBsAg-positive mothers and the contributing factors. Methods: The study was conducted on a group of 87 children, ranging from nine months to under 36 months, born to HBsAg-positive mothers and received immunoprophylaxis within 24 h after birth followed by a national immunization schedule at the Community Health Center (CHC) in three administrative cities of DKI Jakarta. We measured the levels of HBsAg and anti-HBs, and utilized ordinal logistic regression models to identify factors that influence the anti-HBs titers after vaccination. Results: Out of 87 children, only one child had positive HBsAg results. The data showed that 88.5% of the children had seroprotection with anti-HBs levels ≥10 mIU/mL. Additionally, 48.3% of the children had a high protective response with anti-HBs levels ≥100 mIU/mL, while 11.5% had a non-protective response. Children under one year of age, with a family history of HBV carriers, and who received five doses of the HB vaccine exhibited higher levels of anti-HBs titer category with adjusted OR 3.9 (95%CI: 1.3–11.6), 5.3 (95%CI: 1.1–27.4), and 8.3 (95%CI: 2–34.8), respectively. Conclusion: The administration of HBIG and HB vaccine successfully prevented vertical transmission, resulting in a high seroprotection rate. © 2024