Undesirable features of polymeric materials include insufficient thermal stability under specified exploitation conditions and too high flammability. These features depend on the chemical structure of polymer macromolecules, and composition of polymeric composites. Polymeric materials with increased thermal stability and improved resistance to the action of fire are produced with the use of various types of fillers with nanometric dimensions. Among numerous nanofillers, carbon-based nanofillers such as graphite nanoplatelets, carbon nanotubes and graphenes (graphene oxide, reduced graphene oxide and modified graphene) play an essential role. The aim of this report is to highlight the latest findings concerning the effect of carbon fillers, mainly graphene and carbon nanotubes on the thermal properties and flammability of polymer nanocomposites.