Cities drive some of the most urgent sustainability challenges that societies face today, including inequality, resource consumption and climate change. Meanwhile, economic growth is increasingly being viewed as a challenge for sustainable development, generating a call for post-growth transformation. In recent years, the notion of a sharing economy has spread to cities across the globe and has been adopted as a solution for addressing multiple urban sustainability challenges. The sharing economy is often associated with multinational corporations such as Airbnb and Uber, however, there is a parallel movement of emerging social practices. This study investigates the case of the multi-actor sharing economy in Gothenburg, Sweden, in order to assess the capacity of an emerging grassroots movement to contribute to economic transformation towards a post-growth model. The findings demonstrate how the grassroots movement show potential for radical change as they adopt and replicate goals and visions aligning with post-growth transformations. Further, the results show how the movement is reconfiguring urban governance relations through i) transformative leaders and ii) intermediary organizations enabling cross-sectorial actor relations to emerge. However, the findings also point to emerging risks of disempowerment and limited capacity of grassroots which induce three policy suggestions to strengthen the transformative capacity of the movement. These are to i) organize multi-actor exercises that foster collective visions, ii) support the development of co-operative business models for grassroots, and iii) establish a Community Support Centre. The study concludes that Gothenburg is an example of a type of sharing economy with potential for post-growth transformation.