The local structure of cesium-borosilicate glasses with various Cs₂O and B₂O₃ proportions and constant SiO₂ content (50 mol %) is studied with ¹¹B, ²⁹Si, and ¹³³Cs MAS NMR spectroscopy. The portions of three- and four-fold Si atoms are determined, as well as the concentrations of various silicate Qⁿ units. Our experimental data are compared with the predictions of Dell’s model and thermodynamic modeling for sodium–borosilicate analogs of the glasses studied.