<p>This study examines why efforts to establish a comprehensive and sustainable database for returnee migrants in Bangladesh have remained fragmented despite repeated initiatives and extensive data collection. While Bangladesh maintains a well-developed system for monitoring outgoing labour migration, return migration continues to be weakly documented and poorly institutionalized. Drawing on Norman Long’s actor-oriented approach and interface analysis, the study explores how interactions among state agencies, non-governmental organizations, and returnee migrants shape returnee migrant data governance. The analysis is based on 21 qualitative interviews, including 16 key informant interviews with government officials, NGO representatives, international organizations, and experts, and five in-depth interviews with returnee migrants. The findings show that returnee migrant data are produced across multiple institutional sites including security agencies, government bodies, and NGOs but remain fragmented due to overlapping mandates, contested authority, project-based data systems, and limited data-sharing arrangements. NGOs retain significant control over grassroots-level data, government agencies compete over responsibility, and returnee migrants engage selectively with data systems based on trust and perceived risk. The study demonstrates that data governance challenges are primarily institutional and relational rather than technical. It identifies existing institutional interfaces, particularly at local and district levels, that could support a coordinated returnee migrant database if better aligned. By conceptualizing data infrastructures as sites of negotiation, the study contributes to migration governance literature and offers policy-relevant insights for strengthening returnee migrant data systems in Bangladesh.</p>