In this chapter, we present a case study of the emerging smart city ecosystem. With rapid global urbanization projected to place nearly 70% of the world’s population in cities by 2050, urban centers face mounting challenges in infrastructure, resource management, safety, and social equity. We explore how Web3 technologies, including Decentralized Autonomous Organizations (DAOs), Decentralized Identifiers (DIDs), decentralized finance (DeFi), and decentralized applications (DApps), can address these issues by replacing traditional top-down governance with a decentralized, value co-creation framework. More importantly, using the conceptual QCity Eco platform, built on the pillars of Web3, we demonstrate three transformative value co-creation scenarios. First, asset digitization tokenizes individual-owned resources (e.g., solar panels) into NFTs managed through DeFi, advancing sustainability and generating creative revenue streams. Second, community-driven governance and tokenized incentives encourage citizens to share their diverse data sources, transforming them into collective-value assets that enable intelligent city services, foster participatory governance, and support data-driven urban planning. Third, collaborative decision-making fosters inclusivity by empowering all stakeholders, including individual citizens, to co-design and collectively shape the city’s future.