In recent years, scholarship on international organisations (IO) has devoted increasing attention to the relations in which IOs are embedded. In this article, we argue that the rationalist-institutionalist core of this scholarship has been marked by agentic, repressive understandings of power and we propose an alternative approach to power as productive in and of relations among IOs. To study productive power in IO relations, we develop a theoretical framework centred on the concept of ‘metagovernance norms’ as perceptions about the proper ‘governance of governance’ that are shared among IOs in a governance field. Drawing on discourse theory, we contend that metagovernance norms unfold productive power effects, as dominant notions of how to govern well and effectively (i) fix meanings, excluding alternative understandings and (ii) are inscribed into practices and institutions, hence reshaping inter-organisational relations over time. To illustrate our framework, we trace metagovernance norms in discourses among health IOs since the 1990s. We find a historical transformation from beliefs in the virtues of partnerships, pluralisation, and innovation, towards discursive articulations that emphasise harmonisation, order, and alignment. Moreover, we expose the productive power of metagovernance norms by showing how they were enacted through practices and institutions in the global health field.