ABSTRACT Migration towards the EU has passed for many decades via Russia, Central Asia, and the Caucasus, using Ukraine and Belarus as transit states, yet it adopted new forms under Russia’s intensified ‘hybrid’ warfare, and its 2022 military invasion of Ukraine. This paper seeks to uncover: (1) how formal policies and informal practices were interconnected in the governing of the migration ‘crisis’ on the EU’s eastern border with Belarus (2021–2023); and (2) what different modes of power were used to govern it. The paper advances a polycentric governance perspective. It demonstrates that crisis governance was not simply pursued by the Belarussian government and the EU as direct parties to the conflict. It involved a plethora of other stakeholders including Middle Eastern states, Russia, and travel agencies as non-state actors, all entangled in specific relationships with one another. This paper’s contribution is to show how relational dynamics among these stakeholders governed the crisis via a mixture of formal and informal practices that entailed different levels of coersion. The polycentric perspective advanced here is more useful when studying crisis governance than statist, multilevel governance, or EU-centric approaches emphasising institutional logics, as it emphasises relations among actors, and the power that shapes these relations and the governance system as a whole.