The thematic and geographical expansion of EUmigration policies has gone along with an increasing mobilisation of pertinent international organisations such as the IOM and UNHCR. Combining insights from the external governance approach with IR debates on international institutional complexity, this article examines the dynamics behind this ‘multilevelling' of EU external policies. Three strategies of institutional interplay are distinguished: counterweight, whereby international organisations act as independent complement or corrector to EU policy; subcontracting, referring to the outsourcing of EU project implementation to international organisations; and rule transmission, a process in which international organisations engage in transferring EU rules to third countries. Whereas greater organisational authority and autonomy have allowed the UNHCR to keep an independent voice as counterweight to EU action, both the UNHCR and IOM have become increasingly involved in the implementation of the EU's ‘global approach' to migration via subcontracting and rule transmission. In sum, these processes shed a new light on the role of the EU within the international migration regime complex.