The contributions of EU agencies are significant components of the EU policy response to migration issues. The extent to which this has come to be in the context of migration, and the successive waves of policy and institutional reforms concerning these agencies in the last decade, pose several questions that the existing literature is only partially equipped to answer. This paper addresses this gap by charting the evolution of EU agencies through documentary analysis, reflecting on the meaning of this evolution for current trends in European integration as captured by the recent theorization on de novo bodies. Findings demonstrate that, far from being static entities, these bodies have constantly deepened their reach into the formation and application of migration policy, while posing no substantial erosion of the authority of the Commission. This incremental empowerment has created accountability issues from the beginning, many of which are still far from being resolved.