It is now widely acknowledged that to make adequate and timely progress in the direction of biodiversity mainstreaming, three critical aspects – previously overlooked or insufficiently handled by supranational policies – need to be emphasised and further explored in their transformative potential: 1) The establishment and operation of bottom-up and especially City- and Community- driven initiatives, which may adequately complement the Country level National Sustainable Development Plans and Green Growth Strategies; 2) The introduction and refinement of appropriate methodologies, and capacity-building activities, to enable the engagement of all key societal stakeholders (notably including market players, citizens and local government actors) in concerted actions to restore the most compromised elements of the natural environments; 3) Continuous work on enabling nature-based solutions by identifying the connections, and addressing the disconnects, between biodiversity conservation and social, economic, and technological challenges. To meet the requirements of the EU Biodiversity Strategy for 2030 and of the recent Commission proposal for a Nature Restoration Regulation, the UNP+ consortium proposes a 3-year long action research plan, engaging 11 academic partners and 5 European Cities as “Lighthouse” and “Greening” testbeds, ready to share knowledge and scale up from their ongoing experiences in UNP design and NBS implementation & scaling, to a next-generation strategy for urban and periurban ecosystem transformation, mainstreaming biodiversity, ecosystem services, and natural capital in urban policies and economies through adopting a whole of society approach.