Confronting the severe health threats and environmental impacts of Cr(VI) in aquatic environments demands innovative and effective remediation approaches. In this study, Graphene oxide (GO)-decorated poly(dimethyl amino ethyl methacrylate) (PDMAEMA) brush nanocomposites (GOP1, GOP2, GOP3, and GOP4) were fabricated using atom transfer radical polymerization (ATRP) by the “graft from” method. The resulting nanocomposites were utilized for removing Cr(VI) with good adsorption performance due to the electrostatic interaction of protonated nitrogen groups in the brush chains with negatively charged particles in the solution. The kinetic model of pseudo-second-order best represented the contaminants' adsorption characteristics. The Weber–Morris model further indicated that surface adsorption and intraparticle diffusion mechanisms primarily controlled the adsorption procedure. Additionally, the Langmuir and Temkin isotherm models were found to most accurately represent the adsorption characteristics of the pollutants on the nanocomposites, and GOP4 can achieve the maximum adsorption capacity of 164.4 mg·g–1. The adsorbents' capacity maintains above 85% after five cycles of adsorption-desorption. The nanocomposites in this study demonstrate promising potential for eliminating Cr(VI) from aqueous solutions.