Type-2 fuzzy set (T2FS) is a set produced by expanding the membership function in fuzzy set (FS) into type-1 fuzzy set (T1FS). Because it has the advantage of expressing deeper uncertainty and can greatly enhance the ability to describe the uncertainty of the real world. Therefore, the research on decision-making theories and methodologies in type-2 fuzzy environment has been booming in recent years. This paper provides a systematic review of the development of type-2 fuzzy decision-making theories and methodologies, which is helpful to sort out the development context of this field, clarify the research trend of existing work, and lay a solid foundation for future research work. First, the development process and basic theoretical research status of T2FS are introduced.Then, the research status of decision-making fundamental theories (information fusion theory, preference relation theory, and measure theory) and decision-making methods based on type-2 fuzzy information are summarized respectively. Finally, prospects for future research directions of type-2 fuzzy decision-making theories and methodologies are presented.