Purpose: This study examines the background of Singapore’s White Site system and analyzes its implementation process and the roles of public and private sectors. Based on these analyses, it identifies implications for promoting private development and creating innovative urban spaces through a flexible planning system. Method: A literature review was conducted on Singapore’s urban planning and operational practices. The development projects of white sites in the Marina Bay area was selected as a representative case study. Detailed project data, including tender announcements and contracts, were analyzed to examine development processes, policy approaches, and institutional mechanisms. Result: Singapore’s urban planning system is based on an integrated management structure led by Urban Redevelopment Authority (URA) and supported by close inter-agency collaboration. The White Site system allows mixed-use development without predefining land-use functions. This approach improves land-use efficiency and economic value. It also helps reduce market risks by allowing post-development adjustments in land use. The Marina Bay cases suggest that effective development requires more than just regulatory relaxation. The results highlight the need for land supply mechanisms aligned with development objectives, a clear division of roles between the public and private sectors, and concrete institutional designs such as the Master Developer approach.