Abstract: Within research on socio-technical system transitions, foresight has been discussed as a core element of reflexive governance, aiming to facilitate transformative change towards sustainability in response to the limitation of conventional approaches that could not properly reflect uncertainties, complexities, long-term planning process, integrated knowledge, systemic approaches and diverse future pathways. In this regard, 2030 Seoul Plan, a 20-year long-term Basic urban plan in Seoul, explicitly shows a remarkable and meaningful turn from conventional planning approaches to participatory foresight approaches, triggered and driven by strong political leadership. This paper explores whole processes of 2030 Seoul Plan that has overcome the inertia of path dependency, and analyzes main drivers and barriers of this change. The analysis provides an insight regarding how the participatory foresight at megacity scale can be implemented. It also develops the analytical framework of participatory foresight from various related literatures to evaluate 2030 Seoul Plan and find strengths and weaknesses of it. Four findings are mainly addressed in this study. First, integrated knowledge was generated among three main participants groups including citizens, experts and different departments of Seoul Metropolitan Government (SMG). Also, the adaptivity of strategies and institutions, as well as learning was developed during the processes of 2030 Seoul Plan. The new cooperative cultures and interactive strategies were developed by inclusive discussion among the participants. Learning process can be also found from the processes, yielding positive outcomes. Thirdly, citizen participatory planning process makes the plan continuously regardless of the short-term electoral period. Finally, iterative and participatory goal formulation was planned but not yet implemented in 2030 Seoul Plan. As this was established recently, further research is required to look into this more thoroughly.