Urban systems globally experience significant and interlinked societal challenges including pressures on public health and well-being and growing inequalities and social disruption. At the same time, urban systems are particularly vulnerable to impacts of climate change and suffer from degraded or lack of natural ecosystems to help alleviate these impacts. A promising approach to deal with these challenges is to work with nature’s capacity and qualities in a sustainability perspective. Working with nature in urban settings has advantages over other approaches: multi-functionality, multi-benefits and cost-effectiveness. Nature Based Solutions (NBS) are interventions that seek to restore, improve, enhance or conserve natural capital and biodiversity in terms of habitats or ecosystems. Subsequently, these ecosystems provide enhanced multiple ecosystem services that contribute to social and economic benefits, reducing the urban societal challenges. They can help build climate resilience in cities, improve liveability, and in collaboration with other urban priorities contribute to building inclusive communities, closing social equality gaps, while promoting innovative businesses and jobs. The aim of Regreen is to generate evidence for how Nature-based solutions (NBS) underpinned by improved urban governance, and public and private participation can systematically integrate ecosystem services and biodiversity and advocate their benefits and values in urban planning to meet societal challenges including climate change resilience, public health and well-being, and social inclusion. Co-creation with urban planners, citizens and business in urban living labs and educational programs for children ensure long-term sustainability of solutions, and support to business development assist further realization. This to accelerate the crucial transition toward smart, green and healthy cities in Europe and China.