Research on the synthesis of advanced composite materials is an important area of research on the visible-active photodegradation of environmental pollutants. Novel hybridized structures of graphitic carbon nitride (g-C3N4) are synthesized by a facile one-step in-situ method. Black titanium oxides, TiO, Ti2O3, a mixture of TiO + Ti2O3, and a reference material, white TiO2 P25, are used for the synthesis of the hybridized g-C3N4 and further decorated with Ag nanoparticles. Physicochemical and optical properties of the obtained materials are characterized by various techniques. XRD patterns revealed that the structural regularity of g-C3N4 and titanium oxide(s) is maintained in the composites. However, the main diffraction peak for g-C3N4 is prominently shifted to a lower 2-theta along with a decrease in the intensity, indicating the formation of g-C3N4 nanosheet heterojunction. Vibrational spectra of the composites showed signature IR peaks for g-C3N4 and demonstrated an enhancement in the vibrations after modifications, and further supported the XRD results. A distinct red-shift in the optical spectra of g-C3N4 upon modifications with black titanium oxide(s) demonstrated an enhanced absorbance of visible light, yet on the contrast white TiO2 P25 showed a blue-shift. Under the experimental conditions of simulated solar light, pristine g-C3N4, and its composites g-C3N4/TiO and g-C3N4/Ti2O3 showed moderate activity for the photodegradation of an organic pollutant, rhodamine B. Interestingly, a synergistic enhancement in the photoactivity is demonstrated by the g-C3N4 modified with a mixture of black titanium oxides (g-C3N4/TiO + Ti2O3). On the other hand, the composite synthesized by a post-synthesis method is found less effective in photodegradation reaction.