Optically transparent nanoceramics MgAl2-xO4:Crx (x = 0.005, 0.00005) were synthesized using a thermobaric pressing technology at different pressures (2 GPa–8 GPa). The structure and morphology as well as paramagnetic and photoluminescent properties of the obtained materials were studied using XRD, SEM, optical absorption, EPR and photoluminescent spectroscopy. It is shown that the applied pressure and the content of impurity chromium affect the type and concentration of defects formed in the structure of ceramics as a result of synthesis. The spectral characteristics of the luminescence and excitation of Cr3+ ions and the peculiarities of their change with varying synthesis modes are determined. Using calculations of electron density distributions, it is point out how the covalent character of Mg–O and Al–O bonds affects the lifetime of Cr3+ luminescence. The obtained results indicate the prospects of MgAl2-xO4:Crx nanoceramics for the development of new light-emitting materials.