In this study, different generation of poly(amidoamine) (PAMAM) coated magnetic iron oxide nanoparticles were successfully synthesized via divergent growth approach of dendrimer for the removal of nonylphenol (NP) from water. The characterization of synthesized nanoparticles was performed by XRD, FTIR, TEM, FE-SEM, EPX, and VSM. The results suggested that there is a direct correlation between the number of dendrimer generation and its adsorption capacity; however, the rising generation > 10 could not enhance NP removal efficiency, significantly. The 10th generation of PAMAM-MNP was modified by 4-aminophenol (MNP-G10-pAP) to enhance its adsorption capacity. The kinetic studies were performed after the determination of optimal adsorption conditions (pH, 7; Detention time, 60 min). It was found that Dubinin-Radushkevich (D-R) isotherm and pseudo-second order model are perfectly stimulated the adsorption behavior and kinetic rate of NP uptake. Furthermore, the NP removal efficiencies of 70, 67, 63 and 65% were observed for distilled water, drinking water, well water and treated wastewater, respectively. Finally, it was revealed that the synthesized product had acceptable reusability in eight times and NP removal efficiency decreased by just 15%.