Fiber and matrix-dominant properties of fiber-reinforced polymer composites are important in many advanced technological fields, such as aviation, aerospace, transportation, energy industry, etc. Still, pre-mixing the polymer matrix with nanoparticles may enhance the through-thickness or matrix-dominant properties, and surface treatment of fiber reinforcements with nanoparticles, on the other hand, may improve the in-plane or fiber-dominated properties of laminated composites, as well as interfacial adhesion. A novel manufacturing method that combines a spraying process with nanoparticle/epoxy mixture technique was introduced to incorporate carbon nanoparticles for enhancement of thermal properties of multiscale laminates. Several graphene-based nanomaterials including graphene oxide (GO), reduced graphene oxide (rGO), graphene nanoplatelets (GNPs) and multi-walled carbon nanotubes (MWCNTs) were employed to modify the epoxy matrix and the surface of glass fibers. Multiscale glass fiber-reinforced composites were fabricated from unmodified and modified epoxy, as well as fibers, using the vacuum-assisted resin transfer molding (VARTM) process. The composites obtained combined improvements in both the fiber and matrix- dominant properties, resulting in superior composites. The morphological, rheological, thermal and mechanical properties of the glass fiber-reinforced multiscale composites were investigated. The thermal properties of the epoxy/nanoparticle composites were studied through differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA) and thermal conductivity measurements. The tensile, bending, vibration, interlaminar shear strength (ILSS) and thermal characterization results indicated that the introduction of GNPs, GO, rGO, and MWCNTs enhanced the themo-mechanical properties. The fracture surfaces of the fiber-reinforced composites were examined by scanning electron microscopy (SEM) and the micrographs were analyzed to comment on the mechanical results.