The stabilization of complex fluoroanions derived from weakly acidic parent fluorides is a significant and ongoing challenge. The [SF5]- anion is recognized as one such case, and only a limited number of [SF5]- salts are known to be stable at room temperature. In the present study, glyme-coordinated alkali metal cations (K+, Rb+, and Cs+) are employed to stabilize [SF5]-, which provides a simple synthetic route to a [SF5]- salt. The reactivities of KF and RbF with SF4 are significantly enhanced by complexation with G4, based on Raman spectroscopic analyses. A new room-temperature stable salt, [Cs(G4)2][SF5] (G4 = tetraglyme), was synthesized by stoichiometric reaction of CsF, G4, and SF4. The vibrational frequencies of [SF5]- were assigned based on quantum chemical calculations, and the shift of the G4 breathing mode accompanying coordination to metal cations was confirmed by Raman spectroscopy. Single-crystal X-ray diffraction revealed that Cs+ is completely isolated from [SF5]- by two G4 ligands and [SF5]- is disordered along the crystallographic two-fold axis. Hirshfeld surface analysis reveals that the H···H interaction between two neighboring [Cs(G4)2]+ moieties is more dominant on the Hirshfeld surface than the interaction between the H atom in glyme molecules and the F atom in [SF5]-, providing a CsCl-type structural model where the large and spherical [Cs(G4)2]+ cations contact each other and the [SF5]- anions occupy interstitial spaces in the crystal lattice. The [SF5]- anion, combined with [Cs(G4)2]+, exhibits a very limited deoxofluorinating ability toward hydroxyl groups in both neat conditions and THF solutions.