This work reports the preparation of poly(methyl methacrylate) (PMMA) nanocomposites using in-house made compatibilizer and maleic anhydride-grafted PMMA (PMMA-g-MA) by melt intercalation in the presence of nanoclay, modified with 15-35% octadecylamine and 0.5-5wt% aminopropyltriethoxysilane. PMMA nanocomposites containing 5wt% nanoclay (with and without compatibilizer) were prepared by melt intercalation technique using a single screw extruder. The structural, thermal, and mechanical properties of the prepared nanocomposites were investigated. The X-ray diffraction (XRD) traces and transmission electron microscopy (TEM) images of the nanocomposites reveal the formation of intercalated PMMA nanocomposites. Thermal stability of PMMA nanocomposites improves significantly with the addition of nanoclay and compatibilizer. The PMMA nanocomposite prepared with compatibilizer displays enhanced mechanical properties over neat PMMA and the nanocomposite synthesized without compatibilizer. The maximum improvement of tensile strength, Young's modulus, flexural strength, flexural modulus, Shore D hardness and impact strength for the PMMA nanocomposite prepared with PMMA-g-MA is found to be 8, 98, 15, 21, 13, and 6%, respectively, over neat PMMA.