This exploratory study examines how fragmented and underutilized data systems limit the ability to identify and reach zero-dose (ZD) and under-immunized children in Mali. Using qualitative methods and multi-source data analysis, the study identifies key challenges related to data quality, interoperability, governance, and limited use of data for decision-making. It also tests prototype solutions, including automated data triangulation and geospatial modeling, to improve identification and targeting of ZD children. Findings highlight the need for an integrated, interoperable data platform and strengthened subnational capacity to support timely, evidence-informed immunization planning and action.