This study introduces a novel hydrogel nanocomposite as a superabsorbent for the water decontamination of cadmium ions. The absorbent was prepared by the intercalation of polymerized acrylamide (AAm) and 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) in the presence of montmorillonite (MMT). The structural, morphological, and thermal properties of the synthesized hydrogel were determined by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The prepared organic structure was next tested in the removal of Cd (II) ions from an aqueous solution. Solution pH, retention time, metal-ion concentration, and absorbent dose were the tracked parameters during the removal of Cd ions. Successful elimination of cadmium ions from polluted water, by the absorbent, has been generally achieved under various operating conditions. The maximum Cd removal was observed under operating conditions of pH 5, absorbent dose 0.2 g/L, and time 105 min. The prepared hydrogel was able to absorb 301.5 mg of Cd (II) per each gram of its mass. The elevated absorption capacity of the presented hydrogel (AAm/AMPS/MMT) is explained by the presence of versatile functional groups within its structure and also by the network distributions onto its surface. Ion exchange between the absorbent and Cd (II) is another key factor for the observed absorption activity. The subsequent absorption/desorption cycles of the spent AAm-AMPS/MMT absorbent could show its high reliability in reusing with a display of consistent activity during the capture of Cd ions.