Background <p>Hepatitis B virus (HBV) mother-to-child transmission (MTCT) remains a major global public health challenge. While the World Health Organization has set ambitious targets for elimination of MTCT, achieving these goals in high-burden countries like China requires robust, real-world evaluation of preventive strategies. Our study aims to analyze the effectiveness of preventing MTCT of HBV and the associated risk factors.</p> Methods <p>This retrospective cohort study comprised 16,223 pairs of hepatitis B surface antigen-positive mothers and infants from 2021 to 2023 in geographical regions replete with coverage by preventive measures. We calculated MTCT rates of HBV in different maternal-infant groups and analyzed the risk factors associated with MTCT of HBV.</p> Results <p>The mother-infant pairs in our study exhibited a 99.46% compliance rate for hepatitis B immunoglobulin and 98.87% for the birth-dose vaccine. The overall HBV MTCT rate was 0.60% (97/16,223). When hepatitis B viral protein (HBeAg)-positive women received timely antiviral intervention, MTCT rates were reduced to 0.48%. Multivariate analysis confirmed that HBeAg-positive (adjusted odds ratio [aOR], 132.03 [95% confidence interval {CI}, 18.26–954.41]) and HBV DNA viral load ≥ 2 × 10⁵ IU/ml (aOR, 2.05 [95% CI, 1.30–3.22]) were associated with an increased risk for MTCT. Maternal antiviral therapy (aOR, 0.17 [95% CI, 0.10–0.28]) and infants receiving three doses of hepatitis B vaccine (aOR, 0.07 [95% CI, 0.01–0.76]) were found to be the protective factors.</p> Conclusions <p>This study provides important insights into the factors contributing to HBV MTCT. However, gaps remain with respect to adherence to antiviral therapy, the timeliness of the full-three-dose vaccination series in high-risk infants, and the standardization of treatment protocols.</p> Clinical trial number <p>Not applicable.</p>