In this research work, we report circular type silane-modified CaCO3 (as core) nanoparticles (NP) encapsulated with polystyrene (PS) and polymethyl methacrylate (PMMA) (as double shell layers). These core-double shell [CaCO3-PS/PMMA] hybrid nanostructures were prepared by a stepwise micro-emulsion polymerization and characterized by fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, elemental mapping, differential scanning calorimetry and thermo gravimetric analysis. These core-double shell hybrid nanostructured composites had perfect nanoscale shape with narrow size distribution (average size 120 nm), smooth surface and non-agglomerated structures. These observations reflected the strong interfacial interaction between silanated CaCO3-NPs and polymer NPs, which imply the successful grafting of polymer chains onto the surface of silane-modified CaCO3-NPs.