This research investigates and theorises the role of innovation ecosystem intermediaries in supporting purpose-driven sustainable entrepreneurship. Drawing on qualitative research based on 36 semi-structured interviews with incubators, accelerators, investors and entrepreneurs in the Metro-Vancouver region, findings suggest intermediaries fulfil two critical functions in form of gap filling and problematising. Whereas gap filling covers traditional structural efforts in support of sustainable entrepreneurs such as providing access to networks and resources, problematising entails cognitive work designed to challenge the status quo. I develop theory to connect these practices to literatures on a systemic transition toward responsible entrepreneurship ideology and sustainability transformation.