Circular Economy (CE) is commonly proposed as a means to advance towards the Sustainable Development Goals. Design thinking (DT) has been identified as an innovative problemsolving approach, capable of addressing complex challenges, such as the CE, through multidisciplinary collaboration. Currently, the spaces for multi-stakeholder collaboration have been affected by Covid-19 restrictions, forcing organizations to develop online collaboration capabilities. Accordingly, this study aims to assess the effectiveness of the application of DT to generate CE-based solutions to address a sustainability challenge in an online setting. The assessment particularly addresses the extent to which a purposefully adapted DT process allows to conceptualize sustainability solutions, and, the user experiences in a digital collaboration environment. This research presents the findings obtained from an online DT workshop focused on proposing circular business models to improve the sustainability impacts of urban mobility in the city of Graz, Austria. The event involved 39 sustainability experts from academia, industry, public sector and NGOs, participating in five teams, each led by a workshop facilitator. Three specific activities have been elaborated to embed a focus on sustainability, which are combined with traditional DT exercises, and adapted to a digital environment. We report the outcomes of the online workshop and reflect on the adapted method strengths and weaknesses. DT is supported as a plausible method to conceptualize CE-based solutions, however, sustainability aspects need to be embedded throughout the problem-solving process.