The emergence of the circular economy (CE) paradigm has catalyzed a profound transformation in how contemporary industries approach sustainability, resource efficiency, and business model innovation. Circular economy principles, grounded in the reduction, reuse, and recycling of materials, challenge conventional linear economic models, necessitating the exploration of closed-loop supply chains, product life extension, and digital integration. Concurrently, Industry 4.0 technologies—including the Internet of Things (IoT), artificial intelligence (AI), and real-time data analytics—offer unprecedented capabilities for monitoring, optimizing, and transforming resource flows across industrial ecosystems. This study presents a comprehensive synthesis of the theoretical and empirical literature on circular economy business models, highlighting the mechanisms through which Industry 4.0 facilitates circular practices. Through an extensive review and analysis of case studies across manufacturing, fast-moving consumer goods, electronics, construction, and automotive sectors, the research identifies critical enablers and barriers to circular business model implementation. Key findings reveal that organizations leveraging digital technologies for product tracking, predictive maintenance, and resource recovery are better positioned to capture value from circular operations. Furthermore, collaborative consumption, servitization, and upgradability emerge as dominant strategies for extending product lifecycles and fostering sustainability-driven competitive advantage. The study emphasizes that despite growing momentum, circular business model innovation faces structural, technological, and organizational challenges, including high implementation costs, limited stakeholder engagement, and insufficient regulatory incentives. The paper concludes by offering a conceptual framework for integrating circular economy principles with Industry 4.0 capabilities, providing actionable insights for academics, practitioners, and policymakers seeking to operationalize sustainable and resilient industrial systems.