For the adsorption of copper (II) and zinc (II) ions from polluted water, an efficient inexpensive nanoadsorbent; nickel ferrite-modified montmorillonite nanocomposite was synthesized by co-precipitation of the mechano-chemically modified montmorillonite with the salts of nickel and iron. The natural MMT, modified MMT, and the synthesized nickel ferrite-modified montmorillonite (NiFe2O4-Mod MMT) nanoadsorbent were characterized by several techniques including Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray, surface area analysis, saturation magnetization, and surface zeta potential. Batch studies were carried out on the effect of various parameters including contact time, nanocomposite dosage, solution pH, metal ion initial concentration, and temperature on the adsorption process to optimize its conditions. The equilibrium state was reached after 60 min and 90 min of reaction for Cu (II) and Zn (II) ions, respectively. The optimum conditions were 0.1 g adsorbent dose, pH 5, 13 mg/L initial metal ion concentration, and 298 K temperature for copper (II) adsorption and 0.1 g adsorbent dose, pH 6, 6 mg/L initial metal ion concentration, and 298 K temperature for zinc (II) adsorption. Among the designed kinetic and equilibrium models, the pseudo-second-order kinetic model and Langmuir adsorption isotherm model have controlled the adsorption process for both metal ions. Furthermore, the adsorption mechanism and the reproducibility of the nanoadsorbent were investigated. The maximum adsorption efficiency was 99.23% and 91.67% of copper (II) and zinc (II) ions, respectively.