In the present study, activated carbon-based TiO₂ nanocomposites with carbon loading were synthesized by sol–gel method for photocatalytic, sonocatalytic, and sonophotocatalytic degradation of colored compound in wastewater. The prepared catalysts were characterized by Brunauer–Emmet–Teller surface area analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared analysis (FT-IR). The degradation efficiencies of the synthesized composites were determined by the degradation of Direct Blue-199 dye under three different reactors viz., photocatalytic, sonocatalytic, and sonophotocatalytic. Reaction kinetic modeling was done for these processes and the degradation rate was found maximum for sonophotocatalytic process as compared to individual ones. However, on considering the energy efficiency and degradation efficiency, photochemical reactor was found to be most economical. Therefore, for the treatment of wastewater-containing dye from industries, a photocatalytic process can be applied with further modification.