Non-covalently modified graphene nanosheets were prepared by reduction graphene oxide with hydrazine hydrate and simultaneous non-covalent functionalization via 1-allyl-methylimidazolium chloride (AmimCl) ionic liquid. Atomic force microscopy revealed that AmimCl ionic liquid modified graphene (IL-G) was well-dispersed in a single exfoliation with a thickness of around 0.96 nm in DMF. Subsequently, the prepared IL-G nanosheets were incorporated into polyurethane (PU) to fabricate IL-G/PU nanocomposites by solution blending. X-ray diffraction disclosed an exfoliated morphology of IL-G nanosheets dispersed in the PU matrix, while the fractured morphology of the IL-G/PU nanocomposites showed that IL-G nanosheets presented a wrinkled morphology when dispersed in the matrix. Both techniques revealed homogeneous dispersion and good compatibility of IL-G nanosheets with PU matrix, indicating the existence of interfacial interactions. At 0.608 wt% loadings of IL-G nanosheets, the tensile strength and storage modulus of the composites were increased by 68.5 and 81.1 %, respectively. High thermal properties were also achieved at a low loading of IL-G nanosheets. An approximately 40 degrees C improvement in temperature of 5 % weight loss and 34 % increase in thermal conductivity were obtained at just 0.608 wt% loading of IL-G nanosheets.