Intermediary organisations such as technology transfer organisations (TTOs) are an important mechanism of open ecosystem governance, as they support how ecosystem participants search for knowledge. While scholars have identified TTO activities to support knowledge search, little is known about how these activities relate to the structural dimensions of TTOs or ecosystem-level factors. We propose that ecosystem search scope and problem complexity are key ecosystem-level factors that influence how TTOs support knowledge search. We further argue that coupling, specialisation, centralisation, and formalisation are the key structural dimensions of TTOs. We combine these arguments to develop TTO designs that detail the interplay of the structural dimensions and activities of a TTO given varying ecosystem-level factors. Our paper contributes to research on the open governance of ecosystems, ecosystem structures, and the ecosystem structure–intermediary organisations relation.