Urban Living Labs (ULL) are sites that allow different urban actors to design, test and learn from socio-technical innovations. In this article, I investigate the epistemological roots of ULL, claiming that this new instrument in the realm of urban planning strongly relies on action research, a methodology designed in the 1940s. I explore to what extent ULL and action research are different, identifying past obstacles of action research to design more successful ULL. This paper establishes that ULL are a key element to implement social innovation and that social innovation should lead technological innovation and the recent smart city model to promote smart sustainable cities. The article was prepared in the aftermath of the project “ROCK” (2017–2020) on cultural heritage as a driver for urban regeneration, where ULL played a central role being highly relevant in the context of urban regeneration policies. Key findings support that ULL can contribute to finding a balance between top-down and bottom-up strategies and its comparative qualitative analysis would improve the methodology. Moreover, public and private cooperation should be encouraged and government should lead and act as a key player in innovation strategies. Lastly, geography can contribute to these new challenges by framing past approaches, projecting the future of cities, and finding ways to make them become a reality.