Synthesis of new water-soluble hybrid core–shell titanium dioxide‒triethoxyvinylsilane‒poly(acrylic acid) nanoparticles consisting of titanium dioxide core with modified surface, polyacrylic acid shell, has been considered. The titanium dioxide‒triethoxyvinylsilane‒poly(acrylic acid) nanoparticles have been synthesized in two stages. At the first stage, the titanium dioxide nanoparticles surface has been modified with triethoxyvinylsilane. The so introduced surface vinyl groups of the titanium dioxide‒triethoxyvinylsilane nanoparticles have been used to graft poly(acrylic acid). To do so, free-radical polymerization of acrylic acid in the presence of the titanium dioxide‒triethoxyvinylsilane nanoparticles has been performed at the second stage. Molecular parameters of the obtained titanium dioxide‒triethoxyvinylsilane‒poly(acrylic acid) nanoparticles have been determined by means of static and dynamic light scattering, and their structure has been confirmed by means of infrared spectroscopy. The proposed procedure of modifying the surface of titanium dioxide opens up the possibility of obtaining water-soluble materials based on it for various applications.