The UNaLab project is contributing to the development of smarter, more inclusive, more resilient and more sustainable urban communities through the implementation of nature-based solutions (NBS), which are co-created with and for local stakeholders and citizens. Our three front-runner cities - Eindhoven, Tampere and Genova - are through the establishment of Urban Living Lab demonstration areas experimenting, demonstrating and evaluating a range of different nature-based solutions addressing climate- and water-related urban challenges. The front-runner cities actively collaborate and share their experiences with our seven follower cities - Stavanger, Prague, Castellón, Cannes, Başakşehir, Hong Kong and Buenos Aires – as well as our two observers - Guangzhou and the Brazilian Network of Smart Cities. The project results will enable the development of a European NBS Reference Framework on benefits, cost-effectiveness, economic viability and replicability of nature-based solutions, which will guide cities across Europe and beyond in developing and implementing their own co-creative nature-based solutions.