Poly(methyl methacrylate)/titanium dioxide (PMMA-g-TiO2) nanocomposites were prepared by the direct esterification reaction under mild conditions. Initially, the surface of titanium dioxide nanoparticles (TiO2 NPs) was modified by 3-glycidoxypropyl trimethoxysilane in order to prepare epoxy functionalized TiO2 NPs. The nanoparticles were refluxed in ethanol solution of HCl to convert the epoxy groups into alkyl-hydroxyl units. Subsequently, PMMA chains were attached to the surface of TiO2 NPs by the esterification reaction between alkyl-hydroxyl units at the nanoparticle surface and carboxylic acid terminated PMMA. Fourier transformed infrared spectrometry confirmed the presence of PMMA groups grafted on the surface of TiO2 NPs. X-ray diffraction and X-ray photoelectron spectroscopy revealed the existence of the grafted PMMA of the nanocomposites. An improved thermal property of the nanocomposites was observed by thermogravimetric analysis while transmission electron microscopy images confirmed well dispersed nanocomposites in chloroform due to the functionalization of PMMA brushes.