OBJECTIVE: This study estimated the proportion of children aged 12-23 months who were fully vaccinated in sub-Saharan Africa (SSA), explored geographical disparities across subregions and countries, and identified country-level factors associated with full vaccination (FV). DESIGN: Cross-sectional study. SETTING: SSA. PARTICIPANTS: Children aged 12-23 months. PRIMARY OUTCOME: FV. METHODS: Data for this study were extracted from the most recent Demographic and Health Survey (DHS) conducted in 34 SSA countries between 2012 and 2023. The study included a total weighted sample of 69 218 children. Univariate analyses were performed to describe the socio-demographic profile of the participants and estimate the proportion of FV and the proportion for each of the eight vaccines (BCG, DTP1, DTP2, DPT3, Polio1, Polio2, Polio3, Measles1) at regional level. Bivariate and spatial analyses were produced to examine existing disparities at regional, subregional and countries' income levels. A multivariate logistic regression analysis was fitted for identifying country-level factors associated with FV. RESULTS: 54.1% (95% CI 53.7% to 54.5%) children aged 12-23 months in SSA were fully vaccinated. In addition, substantial inequalities emerged in FV coverage across countries ranging from 23.9% in Guinea to a high of 95.5% in Rwanda. The same pattern was observed for the eight vaccines. Findings also showed that children of birth order 3 and above, who were delivered at home, had received less than four antenatal visits, from poor households and households with more than 5 members, whose mothers were under 25, had primary education level and below, and had no income-generating activities were less likely to be fully vaccinated. CONCLUSION: To achieve WHO's global vaccination coverage target of 90% by 2030 in SSA, vaccination programmes must take account of regional, subregional and national inequities. Our findings also underline the need for interventions tailored to each SSA country's socio-cultural context. ETHICAL CONSIDERATION: Ethical approval was not required as this is a secondary analysis of publicly available data.