We developed a novel three-dimensional (3D) graphene oxide foam/Fe3O4 nanocomposite (GOF/Fe3O4) and evaluated its adsorption performance for Cr(IV) removal. The 3D free-standing graphene foam was firstly synthesized on nickel foam and then oxidized and magnetically functionalized with Fe3O4 nanoparticles to form GOF/Fe3O4. The GOF/Fe3O4 exhibited a very large surface area of 574.2 m(2)/g, a high saturation magnetization of 40.2 emu/g, and a maximum absorption capacity of 258.6 mg/g for Cr(IV) removal, which significantly outperformed the reported 2D graphene-based adsorbents and other conventional adsorbents. The present work may offer a way to prepare a range of 3D magnetic graphene-based adsorbents for application in effective removal of heavy metal ions.