Hypersaline tidal flats (HTFs) are transitional ecosystems commonly occurring in arid and (or) semiarid coastal regions. These ecosystems typically border mangrove forests. Hypersaline tidal flats perform important functions related to the maintenance of coastal biodiversity as well as support socioeconomic and cultural activities in local communities. Despite their importance, HTFs are rarely studied, especially with regard to the understanding of their formation and function. From the premise that the knowledge on the formation of HTF and soil contribute to the understanding of ecological relationships occurring in these ecosystems, a review is presented. Flat topography, coastal dynamics, pronounced hydric deficit, limited frequency, and duration of tidal flooding are the key factors for the formation of these coastal wetlands. The active pedogenetic processes (salinization, gleyzation, sulfidization, and bioturbation) are highly influenced by these factors and present important ecological roles, specifically in regards to carbon and nutrient dynamics. This review presents evidence for the necessity of further studies on the ecological relationships in HTFs, as well as determining the ecological connection between HTFs and other wetlands. Filling this knowledge gap is essential if we are to improve public policies and conservation laws on the protection of all coastal ecosystems.