The global waste problem constitutes one of our grand societal challenges and requires a circular transition of the economy. Achieving such a transition involves a wide range of measures such as regulations, new business models and a change in consumer behavior, as well as multiple actors from politics, business and society. Based on a longitudinal single case study, we show how a circular startup uses interaction practices to progressively densify its business model, network interactions, and participation in societal discourse, and develop a multi-level process model of circular transition. Our findings advance understanding of stakeholder interactions for circular transitions.