An efficient and biocompatible drug nanocarrier is essential for nanomedicines to realize their full therapeutic potential. Here, we investigate the loading of a selective and potent anticancer drug, β-lapachone (β-lap), on a magnetite nanoparticle-decorated reduced graphene oxide (Fe(3)O(4)/rGO) and the in vitro anticancer efficacy of β-lap loaded Fe(3)O(4)/rGO. Reduced graphene oxide (rGO) with magnetic functionality was prepared via electrostatic interaction between positively charged magnetite (Fe(3)O(4)) nanoparticles and negatively charged GO, followed by hydrazine reduction of GO to rGO. The prepared Fe(3)O(4)/rGO shows that Fe(3)O(4) makes the Fe(3)O(4)/rGO hybrid magnetically separable for easy handling during drug loading and release and the Fe(3)O(4)/rGO hybrid exhibits significantly higher loading capacity than that of Fe(3)O(4)/GO, suggesting that restoration of the graphene basal plane upon reduction of GO enhances the interaction between β-lap and rGO. Cellular uptake studies using fluorescently labeled Fe(3)O(4)/rGO verifies successful internalization of Fe(3)O(4)/rGO into the cytoplasm while rGO without hybridized Fe(3)O(4) has poor uptake performance. Furthermore, β-lap loaded Fe(3)O(4)/rGO shows remarkably high cytotoxicity toward MCF-7 breast cancer cells while the blank Fe(3)O(4)/rGO produces no cytotoxic effects. The cytotoxicity results suggest that Fe(3)O(4)/rGO is an efficient drug carrier for anticancer treatments. The fine-tuning of the chemical structures of graphene oxides by reduction chemistry may provide a universal route for controlled loading and release of drugs or biomolecules to construct advanced delivery vehicles.