Abstract: With global population growth, land scarcity, and sea-level rise caused by climate change, the development and utilization of marine space has become a strategic choice for addressing major societal challenges. Floating structures, as a core support for the future blue economy and resilient city construction, are ushering in cutting-edge engineering opportunities. This paper first explores the opportunities for floating structures in providing offshore living space, deep-sea renewable energy (such as wind, solar, and wave energy), resource extraction, and resilient infrastructure. Subsequently, it analyzes eight major challenges in structural engineering within this field: extremely complex load coupling, sustainable material development, novel modular structural forms, precise and efficient construction, deep-sea fluid-structure-sea bed interaction, multi-degree-of-freedom dynamic design methods, marine environmental sustainability, and intelligent monitoring and maintenance. The paper further reviews global research trends in floating structures and introduces the latest research developments in the field of floating structures from China, Australia, the Netherlands, and Singapore.