Overview Seoul’s Magok District was developed from farmland into a large mixed-use area that brought together industrial, residential, commercial, and support facilities. As the area grew, it faced new urban challenges, including traffic congestion, odor complaints, insufficient amenities, environmental concerns, and pedestrian safety issues. While the area was developed as a smart city and embodies an eco-friendly urban model, smart city infrastructure alone was not enough to address the everyday problems experienced by people living and working in the area. In response, the Seoul Metropolitan Government launched the Magok Smart City Living Lab in 2019 as part of efforts to develop Magok as a smart city testbed. What distinguishes the Living Lab is its citizen-led approach: rather than having experts determine solutions first, residents, workers, and visitors participate in identifying urban problems, working with experts to develop solutions, and testing the technologies such as IoT in real-life settings. The approach brings citizens together with the Seoul Business Agency, private companies, experts, and public institutions to co-design and test responses to local problems. The Living Lab has addressed issues regarding traffic, environmental concerns, fire safety, accessibility, and mobility—creating a process through which ideas can be identified, developed, tested, and evaluated for integration into urban services and policies while supporting the advancement of U-City infrastructure and citizen-oriented urban services. Context As urban populations have rapidly concentrated and expanded, the simultaneous increase in buildings and public amenities has led to a range of complex urban problems, including excessive pollutant emissions, environmental degradation, and rising urban crime. In this context, the advancement of smart cities is entering a new phase that goes beyond improving citizen convenience services to fostering new industries and securing emerging technologies based on the Fourth Industrial Revolution. This has increased the need for approaches that can respond to evolving urban