To reach the goals of the Global Hepatitis Elimination 2030 program, Indonesia is now preparing a new regulation for hepatitis B vaccinations for adult population. This study aimed to determine the factors influencing vaccine uptake for hepatitis B in the adult population, and identify barriers to, and facilitators of, hepatitis B vaccination programmes. An explanatory sequential mixed methods design was implemented in this study. We conducted a survey involving 893 participants in the general population followed by 14 in-depth interviews with health providers. The survey found that only 15% (95% confidence interval 13-18%) of participants received at least one dose of the hepatitis B vaccine. Factors associated with vaccine uptake were, living in Yogyakarta compared to living in Aceh, having secondary and higher education compared to primary education, working as a health worker compared to working in other sectors, and having health insurance that covered hepatitis B vaccination compared to not having such health insurance. Our qualitative study also identified several barriers to the adult hepatitis B vaccination programme in Indonesia such as the high cost of vaccination, lack of vaccine availability in certain areas, limited human resources to implement the hepatitis B vaccination programme, and the ineffective dissemination of hepatitis B vaccination. This study highlights that accessibility and affordability of vaccinations are important determinants of vaccination uptake that should be taken into account when planning vaccination campaigns.