Research points to public-private collaboration’s importance for supporting the transformation from linear to circular business models. As little is known of such collaboration, we conducted a 4-year in-depth case study to answer how transformation is affected by two types of tensions: between linear and circular elements and between public and private partners. We find that tensions shape the transformational process into a dialectical pattern, as partners’ institutional differences initially cause them to conflict over whether to focus on linear or circular elements but, over time, arrive at a synthesis. Our findings contribute to circular business model research by illustrating the usefulness of understanding transformational challenges as linear-circular tensions and by illuminating the dialectics of transformational processes.