A graphene-based amine magnetic nanocomposite was synthesized and used for the first time as an effective adsorbent for the preconcentration of the five chlorophenols (CPs) in environmental water samples prior to high performance liquid chromatography-tandem mass spectrometry. The properties of the amine magnetic nanocomposite were characterized by Fourier-transform infrared spectrometry, scanning electron microscopy (SEM) and X-ray diffraction. This novel graphene-based amine magnetic nanocomposite showed great adsorptive ability towards the CPs. The method, which takes the advantages of both nanoparticle adsorption and magnetic phase separation from the sample solution, could avoid some of the time-consuming experimental procedures related to the traditional solid phase extraction. Various experimental parameters that could affect the extraction efficiencies have been investigated. Under the optimum conditions, the enrichment factors of the method for the CPs were in the range from 224 to 518. A linear response was achieved in the concentration range of 0.1–50.0 ng/mL. The limits of quantitation of the method at a signal to noise ratio of 10 for CPs were 0.02–0.04 ng/mL.The proposed method was successfully applied to the analysis of tap and river water samples with recoveries ranging from 81.2 to 106.5%. This work not only proposes a useful method for environmental water sample pretreatment, but also reveals great potentials of amine magnetic graphene as an excellent sorbent material in analytical processes.