This study is focused on the kinetics and adsorption isotherms of amine-functionalized magnesium ferrite (MgFeO) for treating the heavy metals in wastewater. A sol-gel route was adopted to produce MgFeO nanoparticles. The surfaces of the MgFeO nanoparticles were functionalized using primary amine (ethanolamine). The surface morphology, phase formation, and functionality of the MgFeO nano-adsorbents were studied using the SEM, UV-visible, FTIR, and TGA techniques. The characterized nanoparticles were tested on their ability to adsorb the Pb, Cu, and Zn ions from the wastewater. The kinetic parameters and adsorption isotherms for the adsorption of the metal ions by the amine-functionalized MgFeO were obtained using the pseudo-first-order, pseudo-second-order, Langmuir, and Freundlich models. The pseudo-second order and Langmuir models best described the adsorption kinetics and isotherms, implying strong chemisorption via the formation of coordinative bonds between the amine groups and metal ions. The Langmuir equation revealed the highest adsorption capacity of 0.7 mmol/g for the amine-functionalized MgFeO nano-adsorbents. The adsorption capacity of the nanoadsorbent also changed with the calcination temperature. The MgFeO sample, calcined at 500 °C, removed the most of the Pb (73%), Cu (59%), and Zn (62%) ions from the water.