In this study, we have developed a simple, versatile, and rapid solvothermal process for the preparation of sodium metal fluoride (NaxMFy) nanopowders (NaCoF3, NaMnF3, and Na3FeF6) using a microwave digestion system. Microwave heating significantly reduces the reaction time compared to conventional heating methods. The NaxMFy nanopowders have cluster structures consisting of small primary nanoparticles, thus resulting in a large surface area of >60 m2 g−1. The effect of an essential additive is also investigated to confirm the optimal conditions for obtaining large‐surface‐area NaxMFy nanopowders without impurities. We expect that this study will promote further research into the development and application of various nanostructured NaxMFy materials.