A green and facile method for the preparation of gelatin functionalized graphene nanosheets (gelatin–GNS) was reported by using gelatin as a reducing reagent. Meanwhile, the gelatin also played an important role as a functionalized reagent to prevent the aggregation of the graphene nanosheets. The obtained biocompatible gelatin–GNS exhibited excellent stability in water and various physiological fluids including, cellular growth media as well as serum which were critical prerequisites for biomedicine application of graphene. Cellular toxicity test suggested that the gelatin–GNS was nontoxic for MCF-7 cells, even at a high concentration of 200 μg mL⁻¹. Furthermore, the anticancer drug was loaded onto the gelatin–GNS at a high loading capacity via physisorption for cellular imaging and drug delivery. The doxorubicin/gelatin–GNS composite exhibited a high toxicity to kill MCF-7 cells and experienced a gelatin-mediated sustained release in vitro, which has the potential advantage of increasing the therapeutic efficacy. Therefore, the gelatin–GNS could be selected as an ideal drug carrier to be applied in biomedicine studies.