Urban living labs (ULLs) are progressive forms of interventions that aim to fulfil the sustainability ambitions of cities and communities. They provide opportunities to translate new ideas into practice. The increasing interest among researchers, practitioners, and policy makers in understanding sustainability transitions (ST) has brought new forms of experimentation through which cities and communities can be governed. Recently, there has been increasing attention towards the concept of circular economy (CE). This term promises the creation of distinct city systems in which material flows can be managed efficiently. In this article, we explore how ULLs can become pathways of sustainability transition towards innovative city systems from a circular economy perspective. By adopting a series of systematic analyses, i.e., multiple correspondence analysis and content analysis, we demonstrate the main pathways of circular economy-oriented innovative city systems that have been used in the literature. As a result of this work, we identify the main pathways, namely knowledge production, policy making, co-creation, geographical embeddedness, urban transitions, networks of cooperation among institutions, culture change, and collaborative engagement.