The circular economy can enable small and medium-sized enterprises (SMEs) to address sustainability challenges and facilitate the transition from the linear economy. Understanding ecosystem strategies and their implications for circular business model implementation is vital for a successful circular economy transition. Therefore, we seek to answer the following research question: How do SMEs’ circular ecosystem strategies influence business model implementation to achieve circularity goals? Drawing on a multiple case study of 31 SMEs from the food processing industry, our research provides insights into four ecosystem strategies: visioner, synergizer, explorer, and amplifier. These circular ecosystem strategies are contingent on the ability of SMEs to adopt an appropriate role in the ecosystem (leader or complementor) and on the state of ecosystem evolution (emerging or established). In addition, we elucidate activities dealing with the design, development, and commercialization of the circular business model that relate to the ecosystem strategies identified.