Salt marshes are among the most valuable ecosystems on Earth; however, they face ubiquitous cliff erosion at marsh edges globally. Understanding the mechanisms underlying the formation and evolution of marsh-edge cliffs has become an urgent necessity in the field of Earth science. However, owing to the complexity of marsh habitats at the interface between land and sea, our knowledge of marsh-edge cliffs remains limited. Through a literature review, we examined global research on cliff erosion at marsh edges to improve understanding of this process. First, by reviewing the influence of environmental factors such as hydrodynamic forces, sediment substrates, and biological processes, we discuss their coupling effects across spatiotemporal scales. Second, we conceptually examined three prevailing frameworks: “differential deposition fluctuations”, “self-organization”, and “autocyclic retreat”. By analyzing their differences and connections, we further discuss the comprehensive mechanisms of the formation and evolution of marsh-edge cliffs. Third, the development process and application scope of relevant mathematical models of marsh-edge cliff formation and evolution are introduced and discussed. Finally, we identified several problems to be solved following current transdisciplinary research trends in hydrodynamics, geomorphology, and ecology. Future research on the mechanisms driving marsh-edge cliff formation would be beneficial for deepening the current insights into salt marsh erosion and degradation, which can be used to identify early warning systems for vulnerable habitats and guide ecological restoration in response to global change and anthropogenic impacts.