Organic dyes are widely employed globally by the chemical and textile industries. The need to handle water effluent from the dyeing process, to mitigate environmental pollution, cannot be overemphasized. For instance, reactive blue dye is extensively utilized in the textile sector, and controlling its disposal and degradation is crucial in safeguarding the environment. Titanium (IV) tetraisopropoxide was used to synthesize titanium dioxide TiO₂, which was then doped with ferric oxide Fe₂O₃ to create a co-doped TiO₂-Fe₂O₃ photocatalyst. This photocatalyst was employed to degrade blue dye in water under sunlight irradiation. The characterization of the photocatalysts was performed using various techniques: Fourier Transform Infrared (FTIR) Spectroscopy to determine the chemical composition, Scanning Electron Microscopy (SEM) to examine the morphology, X-ray Diffraction (XRD) to assess the crystallinity, and UV–vis Diffuse Reflectance Spectroscopy (DRS) to analyze the light absorption properties. Doping TiO₂ with Fe₂O₃ reduced the photocatalyst's bandgap from 3.76 eV (in pure TiO₂) to 2.83 eV, enhancing its absorption properties in the visible light spectrum, as confirmed by UV-DRS. This improvement in light absorption is consistent with the degradation results of the blue dye, achieving a complete 100% removal efficiency after 120 minutes of sunlight irradiation. This study demonstrates that the photocatalyst is chemically stable and can be reused multiple times. After four cycles, the removal efficiency decreased by less than 15%, indicating its durability and reusability. The doped photocatalyst exhibited increased efficiency in harnessing solar energy to generate electron–hole pairs, resulting in superior photocatalytic activity. This method eliminates the need for electricity, making it both eco-friendly and cost-effective.