Enhancing both interfacial strength and electrical conductivity in carbon fiber (CF)-reinforced epoxy composites remains challenging. Here, poly(acrylonitrile-co-glycidyl methacrylate) (PAG) was synthesized as a reactive sizing agent, confirmed by ¹H-NMR and FT-IR. To impart electrical functionality, reduced graphene oxide (rGO) and azide-functionalized rGO (rGO-N₃) were incorporated into PAG; azide groups were verified via XPS and EDS. Electrical properties of the PAG-based hybrid films were evaluated, and the optimal formulation was applied to CFs to assess conductivity at the fiber level. SEM and EDS revealed surface morphology changes. Single-fiber microcomposites were fabricated by embedding fibers in epoxy droplets, followed by tensile testing and fracture surface analysis to assess interfacial behavior. This strategy combining a reactive polymer and functional nanofillers offers a versatile route for high-performance CF composites.