Atomic oxygen (AO) is a dominant component of the low earth orbit and can erode most spacecraft material. We demonstrated the application of graphene to enhance AO erosion resistance of spacecraft polymers. Graphene-reinforced epoxy resin nanocomposites were prepared by solidification of epoxy resin in solution with dispersed graphene flakes and their AO erosion resistance was investigated in a plasma-type ground-based AO effects simulation facility. The nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. Results based on erosion kinetics revealed that a 46 % decrease in mass loss and a 47 % decrease in erosion yield were achieved by addition of only 0.5 wt% of graphene. Further analysis of the surface morphology and composition showed that the graphene nanoflakes could serve as barriers to protect underneath from AO erosion. Thus, this approach provides a novel route for improving durability and reliability of spacecraft material, especially polymers.