Using the examples of the UN Development Programme and the UN Food and Agriculture Organization, this article aims to analyze how the role of international organizations (IOs) is being changed through the incorporation of South-South cooperation (SSC) narratives and practices into their activities. Despite increased interest in the role of SSC in global governance, few empirical researchers get inside these organizations to see and analyze how this form of cooperation impacts IOs and how the latter adapt to these changes. Based on field work and participant observation, the article presents some results on the mechanisms of IOs in their efforts to permanently readapt to the international environment and, at the same time, participate in the configuration of the international scene. The main argument is that the revival of SSC by rising powers has offered the man opportunity to establish individual and collective strategic partnerships with IOs. In doing so, these powers used SSC modalities to engage several redirections of IOs' governance to lift SSC to the top of the international agenda. IOs first resisted these changes and then readapted by using these strategic partnerships as a means to reaffirm their role in the international system's hierarchy as main institutions promoting SSC.