For the first time, MgAl2O4 nanoceramics functionalized with carbon dots were prepared by thermobaric synthesis. A comprehensive characterization of the obtained MgAl2O4: C nanocomposites is performed using XRD, SEM, XPS and Raman spectroscopy. It is shown that the technological modes of synthesis used make it possible to minimize the interaction of carbon with the oxide sublattice of the solid-state host and promote the stabilization of carbon dots. The types of optical centers and the nature of photoluminescence are determined by optical spectroscopy and photoluminescence spectroscopy with stationary and laser excitation. The synthesized MgAl2O4: С nanocomposites are transparent in visible spectral range, and absorption in the UV spectral range is associated with optical transitions both in the intrinsic defects of host (F-centers) and in carbon dots. It was shown that excitation-dependent luminescence is associated with continuous energy states of defects on the surface of carbon dots. The results obtained indicate the possibility of synthesizing optical nanoceramics with stable carbon dots distributed throughout the volume and having weak interaction with the host.