Nanocomposite superabsorbent hydrogels (NCSHs) were prepared via electron beam radiation-assisted polymerization using carboxymethylcellulose (CMC) and carbon materials as a superabsorbent polymer and additive inorganic nanomaterial, respectively. Carbon materials such as graphite oxide (GO), reduced graphene oxide (rGO), and activated carbon (AC) were used as additives. The chemical structure and morphology of the prepared NCSHs and pure superabsorbent hydrogels (SHs) were characterized using Fourier transform infrared spectroscopy and optical microscopy. In the prepared NCSHs, the carbon components were dispersed well in the CMC polymer matrix. The mechanical strength and gel fraction of the prepared materials were measured, and the swelling kinetics were evaluated using distilled water, urea solution, and physiological saline water. The prepared NCSHs using GO and rGO exhibited larger gel fraction and mechanical strength than the corresponding non-composite SHs. Electron beam radiation was more effective than solution polymerization in the syntheses of SHs and NCSHs with large gel fraction and high mechanical strength. The NCSHs prepared by electron beam radiation exhibited comparable swelling capabilities to those prepared by solution polymerization.