In this experimental work, the comparative study of structural defects in gamma-irradiated carbon nanostructured materials (CNMs) including Graphene Nanoplate (GNP), Graphene Oxide (GO), Single-Walled Carbon Nanotube (SWCNT), Multi-Walled Carbon Nanotube (MWCNT), SWCNT-OH, and MWCNT-OH was investigated using Raman spectroscopy to obtain I-D/I-G parameter. All the samples were irradiated by Co-60 in different absorbed doses of 0-100 kGy in air at ambient conditions. Also, XRD, FTIR, FESEM, and HRTEM analyses were used to characterize defects in the CNMs. FTIR analysis of GO confirmed the presence of C-O, C=O, and OH functional groups. Results of HRTEM analysis for GO at 30 and 50 kGy indicated bending and shrinkage of GO edges and creation of carbon onions. Raman spectroscopy of the all samples showed that there was a simultaneous competition between defect creation and graphitization in the CNMs depending on the absorbed dose and the kind of CNM; In which up to 10 kGy, due to breakage of symmetric order of the carbon atoms, the value of I-D/I-G was increased, while graphitization of the carbon atoms at 100 kGy was the predominant effect, except for SWCNT. The minimum values of I-D/I-G parameter belonged to GO and MWCNT equaled 3.9% and 4% respectively.