The mechanical, electrical, thermomechanical, and thermal properties of a thermoset matrix reinforced with pristine carbon nanotubes (1-D) and reduced graphene oxide (2-D) have been evaluated. Epoxy resin was reinforced with 1-D and 2-D nanomaterials in a wide range of load for a detailed study: 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0 wt. %. It is observed that carbon nanomaterials’ dimensionality influences its ability to transfer their unique properties to the nanocomposites. In this work, carbon nanotubes are more suitable than reduced graphene oxide to improve some properties, even though graphene-related materials have outperformed 1-D nanomaterials in other research. Tensile tests of nanocomposites show the best increment, with loads of 0.7 and 0.1 wt. % carbon nanotubes and reduced graphene oxide, respectively. Tensile strength at these loads is ∼120 % higher than epoxy resin, but the load for obtaining the best mechanical performance is different for each nanomaterial. Electrical conductivity measurements show that 1-D nanostructures are able to form conductive paths better than nanosheets. In this work, carbon nanotubes yield up to three magnitude orders higher than reduced graphene oxide. The highest initial storage modulus is achieved by employing 1-D nanomaterials and contributes to improving the thermomechanical stability. Therefore, the dimensionality of carbon nanomaterials impacts the properties of nanocomposites, and each nanostructure is able to improve the matrix at different regions of the load.