The use of reinforcing fillers is a routine way for enhancing the rubber properties. The incorporation of small amounts of nanofillers into the rubber matrix can remarkably improve the mechanical, thermal, electrical, and chemical properties of the rubber nanocomposites. The specific surface properties of nanofillers such as porosity, surface area, and surface activity are the main factors to specify the final properties of the rubber nanocomposites. Therefore, carefully selecting and optimizing filler materials are critical to developing high-performance rubber composites. The most widely used reinforcing nanofillers which are used in rubber industries are introduced here in two categories: carbon-based nanofillers and inorganic nanofillers. Carbon back, carbon nanotube, graphene, silicon carbide, and siligraphene are carbon-based nanofillers that have great results in reinforcing rubbers. The small size of these fillers, high surface area, and surface charges made good dispersion of fillers in the elastomer matrix to form the cellular network structure to increase the tensile strength and elongation at break. Inorganic fillers such as silica, alumina, clays, zinc oxide, double layer hydroxides, boron nitride, and MXenes are another category of nanofillers that alone or in hybrid together or with carbon-based fillers improve the rubber properties. Hybrid systems create a synergistic effect to significantly improve the rubber performance.