Urban Living Labs have become a popular instrument to find solutions to a current pressing challenge that cities face: How can they combine economic prosperity, social cohesion, and environmental sustainability all at the same time? While the normalisation of Urban Living Labs in cities is well evident, a lack of understanding in the nature and purpose of the empirical phenomenon leaves open many challenges yet to be overcome. One particular challenge is about their potential impact to contribute to transformative changes beyond their initial domain. By combining a historical literature review with a comparative case study to three Urban Living Labs in the city of Groningen, the Netherlands, this study explores how the triadic relationship between stakeholder roles, funding options and outcomes generated influences the impact creation of Urban Living Labs. Comparison between theoretical models and empirical experiences hint that opportunity lies within trust building between urban stakeholders in Urban Living Labs in order to contribute to urban sustainability. The study confirms and adds to current theoretical positions taken about how to overcome issues regarding impact creation; a call for a shared ideology and reviewing the concept of power. Also, it shows five ways to start trust building in Urban Living Labs: redesigning funding programs, political empowerment of initiators, the level of abstract as facilitator in collaboration, search for new ways to access effectiveness, and a clarification of the concept itself.