Urban Living Labs (ULLs) are widely believed to provide a safe environment for experimentation, co-creation and evaluation of innovations in real-life settings. A growing number of cities have been adopting ULLs to co-create and test Nature-Based Solutions (NBS). However, many of these cities have been facing major barriers in trying to adopt the ULL approach for implementing NBS. In this study, we seek to identify these barriers and provide a systemic understanding. Barriers are identified by means of workshops and interviews. Subsequently, interpretive structural modelling serves to identify the interdependencies among the barriers, resulting in a structural model of barriers in adopting ULLs for NBS. Our results show that political and institutional barriers are significantly limiting the adoption of ULLs. Moreover, knowledge brokers and other intermediaries, as well as cross-sectoral collaboration, play a key role in getting ULLs adopted. The findings from this study can help cities to develop strategies that overcome the main barriers for ULL adoption in the context of nature-based solutions.