This chapter aims to explore the evolution, principles, and societal implications of the circular economy as a transformative response to resource scarcity and environmental degradation. It begins by contextualizing the emergence of circularity within the broader challenges of global economic growth, climate change, and the limitations of linear production models. Drawing on multidisciplinary perspectives—including economics, engineering, environmental science, and sociology—the chapter examines how traditional industrial systems have contributed to ecological decline through unsustainable resource extraction, waste generation, and energy consumption. The chapter traces the historical development of circular economy concepts, highlighting foundational contributions from scholars such as Kenneth Boulding, Walter Stahel, and Robert Ayres. It emphasizes the systemic nature of circularity, rooted in closed-loop material flows and inspired by natural ecosystems. Key operational principles are discussed, including reuse, recycling, product life extension, and industrial symbiosis, alongside frameworks such as industrial ecology and the Ellen MacArthur Foundation’s three pillars of circularity. Furthermore, the chapter addresses the social dimension of circular economy strategies, underscoring the need for equity, community resilience, and inclusive governance. Case studies from various sectors—such as poultry, urban mining, and pulp and paper—illustrate how waste valorization can generate both environmental and social benefits. The chapter concludes by advocating for a holistic approach to circular transformation, one that integrates technical innovation with cultural change, interdisciplinary collaboration, and long-term sustainability goals aligned with SDG 12.