This chapter provides a comprehensive, interdisciplinary examination of circular design frameworks as critical enablers of transitioning from linear “take–make–dispose” systems to regenerative, value-preserving circular economies. Grounded in systems thinking, lifecycle assessment, and circular economy principles, the chapter synthesizes recent scholarly advances (2015–2024) alongside real-world applications to bridge theory and practice. The chapter systematically analyses leading circular design frameworks, including the Ellen MacArthur Foundation’s Circular Design Guide, Cradle to Cradle®, the Butterfly Diagram, and the ISO 59000 series, highlighting their conceptual foundations, operational structures, and regulatory relevance. It further evaluates key implementation tools, such as circularity indicators, lifecycle assessment platforms, digital product passports, and emerging digital technologies, including AI, IoT, blockchain, and digital twins. Strategic design approaches—ranging from design for longevity, disassembly, and product-as-a-service to resource efficiency and regeneration—are critically assessed for their environmental, economic, and social impacts. Through detailed product- and system-level case studies, the chapter demonstrates how circular design delivers measurable sustainability benefits while enabling business model innovation and regulatory compliance. It also identifies persistent barriers, including economic constraints, technical limitations, cultural resistance, and fragmented legal frameworks. Looking forward, the chapter highlights innovation opportunities and emphasizes the growing integration of circular design with ESG reporting, digital transformation, and global sustainability governance. Overall, the chapter positions circular design frameworks as essential infrastructure for achieving resilient, low-carbon, and regenerative economies within planetary boundaries.