The interior of 237 nm spherical vinylsilsesquioxane nanoparticles has been covalently modified and their surface functionalized under mild conditions to yield a novel type of hybrid silsesquioxane nanoparticles. Data obtained from thermogravimetric and elemental analysis show that the vinyl groups inside the nanoparticles can be easily brominated or hydroborated, leading to the nanoparticles containing 59.9 wt% of bromine or 3.6 wt% of boron, respectively. Our results demonstrate that the vinyl groups inside the nanoparticles are highly accessible, which may lead to the preparation of a host of hybrid organosilica nanoparticles with complex structures. We also show that the surface of the brominated and boronated nanoparticles is unhindered for further amination.