Bentonite is an abundant, cheap and readily available natural clay mineral, with montmorillonite (MMT) as its main mineral composition. MMT possesses excellent ion exchange, adsorption and ion transport properties due to its unique two-dimensional layered nanostructure, abundant pore structure, and high specific surface area. Moreover, it also possesses excellent thermal, chemical and mechanical stabilities. In recent years, MMT has attracted extensive attention in the field of electrochemical energy storage owing to the above excellent characteristics, especially the inherent fast ion (Li⁺, Na⁺, Zn²⁺, etc.) transport properties. Thus, the bentonite-based functional materials have been widely applied to the key components (i.e., electrodes, polymer electrolytes, and separators) of electrochemical energy storage devices and show good application prospects. In this review, the structure and physicochemical properties of bentonite are firstly introduced, and then the research progress of bentonite-based functional materials in the field of electrochemical energy storage, mainly including metal anodes, lithium-sulfur battery cathodes, solid/gel polymer electrolytes, and polymer separators, is comprehensively summarized. On the basis of these facts, the ion transport promotion mechanism of bentonite-based functional materials during the process of electrochemical energy storage is elaborated. Finally, the current problems and challenges faced by application of bentonite-based materials in electrochemical energy storage devices are pondered, and the possible future research directions are prospected. This review provides useful guidance for the design and development of bentonite-based electrochemical energy storage functional materials.