The demand for electrical energy storage (EES) is ever increasing in order to develop better batteries. NASICON-structured Na ion conductor represents a class of solid electrolytes, which is of great interest due to its superior ionic conductivity and stable structures. They are widely employed in all-solid-state ion batteries, all-solid-state air batteries, and hybrid batteries. In this review, their structure, composition, properties, and applications for next generation energy storage are reviewed.