Dependences of the brightness temperatures of the detonation front and detonation products on detonation pressure were determined in the range of 0.7–9.4 GPa by a pyrometric method. The pressure was varied by changing the initial density of the emulsion explosive in the range of 0.43–1.2 g/cm3. Polymer microballoons were used as sensitizer. The dependence of the brightness temperature in the Chapman–Jouguet plane on detonation pressure was found to be nonmonotonic. In the investigated pressure range, the measured temperature values varied from 2250 to 1830 K. A comparative analysis of the application of polymer and glass microballoons as sensitizers was performed. The obtained experimental data were compared with the calculation results available in the literature.