Co-creation of public services implies new roles and responsibilities that, at least potentially, change the balance of control. In this way, it aligns closely with democratic renewal. This paper draws on the outcomes of a collaborative innovation project Co-creation of Service Innovation in Europe (CoSIE) funded under Horizon 2020. CoSIE built upon the idea that public sector innovations can be best achieved by creating collaborative partnerships between service providers (public sector agencies, third sector organisations, private companies) and citizens who receive services directly or indirectly. CoSIE was implemented through ten real-life innovation pilots in different public services across Europe. Results showed how co-creative methods could promote democratic dimensions, increasing the civic participation of marginalised and often voiceless population groups (residents of depleted urban neighbourhoods, disabled people in remote rural areas, citizens adrift from the world of work, and non-EU migrants). Some CoSIE pilots were more successful than others in extending impact beyond their immediate localities and service contexts. The paper highlights common factors that helped share learning and evolve project innovations into the ‘modus operandi’ of institutions and societies.