Making the transition to a circular economy is an important goal for society and individual companies, particularly in resource-intensive manufacturing industries. Yet the complexity and interdependencies of such an undertaking mean that no single company can achieve it alone and ecosystem-wide orchestration is necessary. Based on a qualitative study of six large manufacturing companies (ecosystem orchestrators) and their ecosystem partners, we develop a process model that describes the scarcely understood process of ecosystem transformation toward a circular economy paradigm. We provide evidence that ecosystem orchestrators achieve the transition toward a circular economy in two stages: 1) ecosystem readiness assessment and 2) ecosystem transformation. In each stage, specific and complementary mechanisms are deployed. The article elaborates on ecosystem transformation mechanisms and their purpose, use, and interdependencies in moving toward a circular economy paradigm.