Graphene oxide (GO), as the precursor of graphene, has inspired great research interest over the past few years due to its excellent physicochemical properties and promising applications. Surface modification of GO with polymers is a general route for enhancing its processibility and improving its performance. Although great effort has been put into this field, the surface modification of GO with polymers in an aqueous solution has proven to be problematic due to the restacking of GO. In this work, we have developed a novel strategy for the preparation of GO thermo-responsive polymer nanocomposites in an aqueous solution via a combination of mussel inspired chemistry and a reversible addition–fragmentation chain transfer (RAFT) polymerization. Two simple steps are involved in this strategy. First, GO was coated with polydopamine (PDA) through a self polymerization of dopamine in a weakly alkaline aqueous solution. Then, the thermo-sensitive polymer poly(N-isopropylacrylamide) (PNIPAM), derived from a polymerization, was facilely grafted onto the PDA coated GO (GO-PDA) through a Michael addition reaction. The finally product (GO-PDA-PNIPAM) was characterized in detail by a series of methods, including Fourier transform infrared spectroscopy, thermal gravimetric analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. These results suggested that PNIPAM can successfully and effectively functionalize GO through a rather facile strategy in an aqueous solution, at room temperature and in an air atmosphere. More importantly, GO-PDA-PNIPAM exhibited excellent dispersibility in aqueous solutions and some organic media, and displayed a good thermo-responsiveness. Taking advantage of PDA and polymerizations, this strategy is expected to be extended for the preparation of many other polymer nanocomposites by employing different nanomaterials and monomers. Therefore, the strategy described in this work should be of great research interest for the preparation and applications of nanocomposites.