Tackling grand challenges requires new forms of collaborative innovation to support intricate design processes involving heterogeneous actors. This paper specifically investigates how co- design supports the anchoring of promising novelties into multiple socio-technical systems to accelerate their respective sustainability transitions. A co-design framework adapted to this multi-system context is derived from transition research and design and innovation management research. The framework is validated empirically based on twenty-seven case studies where the novelty to be anchored corresponds to Earth observation data. Contributing to transition research, the paper shows how this multi-system co-design framework provides novelty developers with a diagnostic tool to clarify their anchoring strategy, by framing the relevant actions to conduct at different time horizons. Several enrichments of the anchoring concept are also proposed, highlighting some complementarities between different forms of anchoring and the endless property of the process. Contributing to design and innovation management research, the paper sheds light on co-design in an original perspective by considering a context crossing the usual boundaries of socio-technical systems and focusing on a diagnostic dimension preceding the organisation of collective design sessions. The co- design framework also highlights a so-called “resource-based” form of collaborative innovation aiming to build novelty-based resources for heterogeneous actors facing grand challenges. This approach complements more common “challenge-based” approaches aiming to directly address a targeted challenge.