Nowadays, radiation grafting polymer adsorbents have been widely developed due to their advantages, such as low operating cost, high efficiency. In this research, glycidyl methacrylate monomers by simultaneous irradiation of gamma-ray with a dose of 20 kGy were grafted on polypropylene polymer fibers. The grafted polymer was then modified using different amino groups and tested for adsorption of cobalt ions in an aqueous solution. Finally, modified polymer adsorbent with the high efficiency for cobalt ions adsorption was synthesized and tested for further investigation. Different modes of cobalt ions adsorption were tested in other adsorption conditions, including adsorption contact time, pH, different amounts of adsorbent mass, and different concentrations of cobalt ions solution. The adsorbent structure was characterized with FT-IR, and SEM techniques and illustrated having an efficient grafting percentage and adsorption capability for cobalt removing by batch experiments. The optimum conditions were obtained by a central composite design as follows: adsorbent mass = 0.07 g, initial concentration = 40 mg/L, time = 182 min, and pH = 4.5 with ethylenediamine as a modified monomer and high amination percentage. The features such as inexpensive adsorbent, easy to prepare, high efficiency, and stability allow the radiated-induced grafted adsorbent to constitute one of promising materials for heavy metals remediation.