Abstract Background Socio-demographic and behavioral determinants of Hepatitis B virus (HBV) vaccination and infection among pregnant women (PW) of Mayotte Island (Indian Ocean) are not well understood. Methods Six hundred and seventy-one pregnant women presenting to public antenatal clinics on Mayotte Island were included between September 15, 2008 and September 27, 2009. Socio-demographics, sexual risk behavior characteristics, and data for HBV biomarkers were collected. Logistic regression was undertaken to study determinants of HBV vaccination and factors associated with the risk of HBV infection were assessed using a survival method adapted to interval-censored data. Due to missing data for HBV biomarkers, data were analyzed using multiple imputation (MI). Results Past or recent HBV infection was observed for 35.5% (95% confidence interval (CI): 30.4–40.8) of PW and 18.6% (95% CI: 14.7–23.2) had evidence of HBV vaccination. PW with unemployed and education qualification (adjusted odds ratio (aOR) 2.65, 95% CI 1.52–4.60) and student status (aOR 4.79, 95% CI 1.63–4.07) were better vaccinated against HBV, compared to those without employment and education. Being born on Comoros was associated with a 63% reduction in HBV vaccination (aOR 0.37, 95% CI 0.21–0.65), compared to be born in Mayotte/France. Women with a history of sexually-transmitted infections in the last 5 years had an increased risk of HBV infection (adjusted hazard ratio (aHR) 3.10, 95% CI: 1.13–8.50), whereas those who sometimes used condoms had a 60% reduced risk (aHR=0.40, 95% CI: 0.23–0.69). Conclusions Socio-demographic factors were identified for HBV vaccination, while behavioral factors were observed for HBV infection. These results could help to determine priorities for intervention.