In this study, we develop a novel tool for designing circular systems - the Circular Systems Navigator. While existing tools and frameworks abound for circular product and business model design, a notable gap exists in addressing the requirements of circular systems design. Systems design is highly relevant because businesses need to simultaneously harmonize product, service, business model, and ecosystem design to avoid adverse rebound effects. We employ design science methodology involving 31 expert interviews, user surveys, and an experimental evaluation to develop and validate a practically useful artifact to holistically design circular systems. We advance theory by championing the concept of Circular Systems Design, providing a process model, and addressing the critical issue of Circular Economy Rebound. This contribution marks a substantive step forward in accelerating the implementation of circular strategies and addressing a fundamental theoretical concern within the broader context of the Circular Economy.