ATELIER is a smart city project that demonstrates Positive Energy Districts (PEDs) within 8 European cities with sustainability and carbon neutrality as guiding ambitions. Amsterdam and Bilbao are the Lighthouse cities that will generate an energy surplus of 1340 MWh of primary energy, prevent 1,7 kt of CO2- and 23 t of NOx-emissions, and invest 156 mln Euros to realise their PEDs. Together with district users, ATELIER will showcase innovative solutions that integrate buildings with smart mobility and energy technologies to create a surplus of energy and balance the local energy system. Bratislava, Budapest, Copenhagen, Krakow, Matosinhos, and Riga are the Fellow cities that will replicate and adapt successful solutions. All cities will establish a local PED Innovation Atelier to co-produce locally embedded, smart urban solutions. In the ateliers, the local innovation ecosystem (authorities, industries, knowledge institutes, citizens) is strengthened, enhancing embeddedness and removing any obstacles (legal, financial, social, etc.) for implementation of the smart solutions. The Innovation Ateliers are designed to be self-sustaining and to live on after the project has ended. The ateliers are engines for upscaling solutions within the ATELIER-cities and replication to other EU-cities. ATELIER integrates a high degree of citizen engagement throughout the project, by actively involving local residents (>9000), local initiatives, and energy communities in activities to align technical solutions with citizens’ objectives and behaviour. Each of the cities will develop a City Vision 2050 that creates the roadmap for upscaling the solutions in the long term. ATELIER has the ambition to pave the way for “energy positive cities” in Europe. All ATELIER activities will be monitored (socially and technically), and lessons learned are systematically drawn and disseminated to relevant SET-plan groups, city networks, and innovation forums.