Today, the rise of digitalization is reshaping how products are designed, produced, and consumed, challenging conventional product development paradigms. In response, manufacturing companies are increasingly adopting service-oriented business models through digital servitization, fueling the emergence of smart Product Service System (sPSS). However, the inherent complexity and need for collaborative innovation in smart PSS design requires manufacturing companies to adopt innovative design approaches that enable value-adding solutions to customers. This research addresses critical gaps in early-stage of smart PSS design, particularly in leveraging Digital Twins (DT) technology to facilitate value co-creation and support design decision-making. Despite growing interest in Digital Twins and virtual simulations, their practical application in smart PSS design remains limited, highlighting the need for new design approaches that foster collaboration and innovation in the early design stages.  To address these challenges and opportunities, this research integrates literature reviews, case studies, and empirical analysis to propose the Future Innovation Framework (FIF) and the Super-System Digital Twins (SSDT) approach for smart PSS development. Through industrial case studies, the research provides practical insights and introduces a Digital Twins approach that supports the successful implementation of smart PSS design in the context of global manufacturing companies. The findings indicate that the proposed Digital Twins approach significantly enhances concept visualization, decision-making and design prototyping in smart PSS design. Future research should focus on refining the Future Innovation Framework (FIF) and Super-System Digital Twins (SSDT) approach, exploring their scalability across various industries, and incorporating advanced AI techniques to maximize their potential.  In summary, this research contributes to the theoretical and practical advancements in smart PSS design by demonstrating how FIF and SSDT can foster more effective and innovative approach in global manufacturing companies. The proposed approach provides a robust foundation for future research and industrial applications, promoting the development of sustainable and competitive smart PSS solutions.