We study the structure of the photocatalytic graphene oxide–titanium dioxide (GO–TiO₂) nanocomposites prepared by in situ sol–gel nucleation and growth of TiO₂ on GO sheets. Fourier transform-infrared (FTIR) and X-ray photoelectron (XPS) spectra of these composites indicate that the GO sheets and the TiO₂ nanoparticles interact through Ti–O–C bonds. This chemical interaction is strong enough to ensure mutual stabilization during thermal annealing, and thereby GO inhibits TiO₂ crystallization. In addition, thermal reduction of GO nanoribbons anchored to TiO₂ nanoparticles occurs at a higher temperature and with a lower released energy than in the pure GO powder. Understanding of the mutual-stabilization mechanisms is critical for the rational design of GO–TiO₂ photocatalysts.