While the concept of hybridisation (blending of different organisational forms, logics, or identities) in public administration has gained traction, its interplay with principal-agent dynamics, especially within development cooperation, remains underexplored. Recent shifts towards the “whole-of-society” paradigm in Swedish development cooperation introduce complexities in the inter-organisational dynamics between actors involved. However, our understanding of how these dynamics influence the manifestation of hybridisation in everyday practices is limited. Drawing on the development cooperation experience of Swedish national authorities and data collected from interviews, focus group discussions, and archival documents, this study identifies the interplaying dynamics of three coexisting logics (managerialist, collaborative, and developmental), and two types of hybridisation (specialisation-centric and integration-centric). These findings shed light on the challenges and opportunities the inter-organisational dynamics induce for translating the “whole-of-society” policy paradigm into development practice and outcomes. The study's theoretical and practical implications for hybridisation in public administration and development studies are discussed.