To bridge the gap between the conceptualisation and implementation of circular value propositions, recent research efforts have focused on linking design-driven approaches with circular-oriented innovation. Such approaches can facilitate iterative processes that emphasise co-creation, prototyping, and real-life experimentation, ultimately promoting practical implementation. Still, there is a lack of understanding how companies go through the process of circular-oriented innovation, and how prototyping and co-creation support this process. This article presents a longitudinal case study of a four-year research project in which two academic teams, from Sweden and the Netherlands, collaborated with industrial partners to explore the potential of circular economy principles within the kitchen industry and develop a market-ready circular kitchen. The results indicate that prototyping plays a supportive role in the circular-oriented innovation process by making the concept of a circular economy tangible for stakeholders, facilitating knowledge exchange, and supporting overall developments towards collaborative circular supply chains. However, prototyping too early in the process linked to project deliverables carries a risk for ‘prototype fixation’, fragmented solutions, and missed opportunities for shared value creation. Co-creation was found particularly impactful during the early stages of circular-oriented innovation where it helped guide the project, enabled shared learning, built confidence and commitment amongst stakeholders, and supported the development of solutions tailored to demands of parties involved. The case study provides deeper insights on the role of prototyping and co-creation through diverse stages of the circular-oriented innovation process and extracts several lessons that might aid researchers and practitioners to navigate future circular-oriented innovation endeavours.