Wettability alteration from oil-wet to water-wet state in carbonate reservoirs, which are predominantly oil-wet, using nanofluids containing nanoparticles or nanocomposites is considered one of the most effective strategies for releasing oil adhered to rock grain surfaces and thereby enhancing oil recovery from these reservoirs. Accordingly, in this research, a new nanocomposite named graphene oxide-silica-titanium dioxide (GO-SiO2-TiO2) was synthesized and used to achieve two main goals: to induce significant wettability alteration and to determine its optimum concentration. Additionally, to obtain information about the mentioned nanocomposite and its thermal stability, six methods were used: Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM), X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric Analysis (TGA), Zeta Potential, and Dynamic light scattering (DLS). According to the results of these methods, it was found that the silica and titanium dioxide nanomaterials had uniformly and regularly covered the surfaces of the graphene oxide nanosheets in the nanocomposite, and the nanocomposite also possessed high thermal stability. Then, using the sessile drop method and also slices from a carbonate core, the contact angle values at concentrations of 0 (reference or oil-wet state), 100, 500, 1500, and 2500 ppm of GO-SiO₂-TiO₂ nanofluid were measured to be 147.46°, 93.28°, 44.13°, 25.02°, and 69.71°, respectively. These results indicate that the new GO-SiO₂-TiO₂ nanocomposite exhibits a remarkable potential to induce significant wettability alteration and, consequently, to markedly improve the oil recovery factor in carbonate reservoirs, especially at the optimum concentration of 1500 ppm, which results in the maximum reduction in contact angle from 147.46° to 25.02°.