Even in the 21st century, water contamination has been a big problem and industrial processes are to be blamed for polluted water supplies. The use of sunlight in the process of photocatalysis is an efficient way to purify wastewater. Composites of TiO₂/activated carbon/two-dimensional selenides performed better than either of the individual material or binary composites for this application. A straightforward hydrothermal technique was employed in the synthesis of photocatalysts. The synthesized photocatalytic composites were verified with the help of UV-Visible spectroscopy, FTIR, XRD, and SEM. The heterostructures absorbed nearly all of the sun’s UV and visible light. These photons are then converted into usable reducing electrons and oxidizing species such as ^•O₂ and OH^• to decompose organic pollutants from industrial wastewater. Since there were additional pathways available for charge transfer along with several active edge sites, the composite photocatalysts are proven more active than individual TiO₂ and 2D MoSe₂ components. With the help of a cascade-driven mechanism of electrons, these channels can transmit more charges than single-component heterojunctions. The results provided a realistic method for developing photocatalyst composites powered by solar light for use in industrial wastewater treatment. Results of degradation of methylene blue suggest that the synthesized composites possess better photocatalytic activity. This enhanced photocatalytic activity is not limited to organic dyes. Other hazardous organic pollutants present in industrial wastewater can be decomposed by using this approach.