Islands and reefs in the South China Sea (SCSIRs) are important components of maritime cooperation and ocean governance in the South China Sea (SCS), providing land conditions for a variety of maritime cooperation. The sustainable development of SCSIRs is a cornerstone of coordinated development and cooperative governance in the SCS. As most SCSIRs are coral reefs with a fragile ecological environment and simplified development models, this study aims to quantitatively and multi-dimensionally explore the current status of their sustainable development to add scientific development planning and improve China's own ocean governance capabilities. The scientific assessment of island and reef development is the inevitable choice for sustainable development of SCSIRs. Based on the method of the Fuzzy Analytic Hierarchy Process, Entropy Weight Method, and combined weight, a subject-objective weight coupling evaluation method for the sustainable development of SCSIRs was developed that can reflect their development status relatively objectively and comprehensively. In addition, the Yongxing Dao (the Yongxing Island), the Zhaoshu Dao (the Zhaoshu Island), the Nanxun Jiao (the Gaven Reef), the Meiji Jiao (the Mischief Reef), the Zhubi Jiao (the Subi Reef), and the Yongshu Jiao (the Fiery Cross Reef) were used as case studies to explore the potential of sustainable development of SCSIRs. The results showed that all six SCSIRs had the potential for sustainable development, and the development focus of the SCSIRs was mainly on the three levels of society, resources, and strategy. The ranking of the sustainable development value of the six islands and reefs is Yongxing Dao > Yongshu Jiao > Meiji Jiao > Zhubi Jiao > Zhaoshu Dao > Nanxun Jiao, among which Yongxing Dao has the highest level of sustainable development (64.19) and a clear advantage in terms of social development and geographical location, while Nanxun Jiaohas the lowest level of sustainable development (38.84) due to harsh weather conditions and fragile ecological environment, leading to difficult circumstances when building and living on the reef. Based on the evaluation results and the actual situation, this study comprehensively analyzes the strengths and weaknesses in the development of SCSIRs and proposes the development of regional centers, comprehensive guarantees, characteristic industries, and national defense and rights safeguarding for the development of SCSIRs. Moreover, the study distinguishes the types of islands and reefs along four dimensions and provides social governance strategies and recommendations regarding resource utilization, infrastructure, and maritime cooperation. In these cases, this study can facilitate the formation of high-quality and high-efficiency application pilots for SCSIRs and promote their sustainable development. Thus, it furthers the construction of a modern system for the social governance of SCSIRs, advances the development of the blue economy in the SCS region, provides security for the construction of the Belt and Road Initiative and maritime cooperation, and makes China a strong promoter in the construction of a community of common destiny in the SCS.