Dendritic poly(amidoamine) (PAMAM)-grafted carbon nanotube (CNTD), as a multifunctional hybrid curing component of epoxy-based resins, was prepared using a divergent method. Amino-functionalized CNT was utilized as a core for grafting the first generation of PAMAM dendritic structure by sequential addition of methyl acrylate and ethylenediamine. Epoxy-terminated polyurethane (EPU) and epoxidized novolac resin (ENR) were prepared and used as the epoxy-based polymers of the hybrid composite products. Proton nuclear magnetic resonance spectroscopy was used to study the structure of EPU. Fourier transform infrared spectra were used to prove each of the modification steps during preparation of CNTD. The characteristic peaks of CNTD at 1532 cm−1 originating from combination of stretching and bending vibrations of C–N and N–H bands, respectively, and the peaks at 2930 and 2859 cm−1 assigned to the stretching vibrations of C-H band of methylene groups confirms this claim. In addition, different char residues of CNT and CNTD in thermogravimetric analysis (TGA) curves confirmed addition of the organic parts and successful preparation of CNTD. Structural properties of the hybrid composites were investigated by X-ray diffraction analysis. The hard and soft segment contents of 34.46 and 65.54 wt% were obtained from X-ray diffraction curves. Char contents of 89.6 and 85.6% at 700 °C for the CNT and CNTD shows that the PAMAM modifier content is about 4 wt%. TGA thermograms of the hybrid composites revealed that thermal characteristics of the hybrid composite composed of ENR matrix and high content of CNTD are higher than the other hybrid composites. The ENR-based hybrid composite with 4 wt% of CNTD showed the highest char residue of 55.2% and degradation peak point of 413.6 °C. Morphology of the neat and PAMAM-modified nanotubes were also studied by scanning electron microscopy and transmission electron microscopy.