The photocatalytic evaluation of a novel material based on protonated thiophene-based oligomers (OTn+ where n = 2–5) as sensitizers of TiO2 nanoparticles supported on protonic zeolite-Y (TiO2-OTn+/HY) was carried out. The experimental part of this work refers to methyl orange degradation experiments under visible light irradiation (λmax = 565 nm). A kinetic model that includes an induction time was proposed, where the observable kinetics coefficient indicated that the degradation rate depended on the amount of TiO2 supported on zeolite. A reusability test demonstrated that the TiO2-OTn+/HY is photochemically stable, at least during three degradation cycles, and the in-situ capture experiments showed that the superoxide radicals are the main reactive species in the methyl orange degradation process. In addition, the theoretical part involves the sensitizer optimization by using Density Functional Theory at the M06-2X/6–31+G** level of calculation to achieve the estimations of some electronic properties, such as vertical excitation energies and oxidation potentials, at the same level of theory using Time-Dependent Density Functional Theory, including water as solvent through the SMD solvation model. Oligothiophenes with protonation in the Cα atom were the best to represent the sensitizers in the TiO2-OTn+/HY material, with excitation energies that correspond to the visible light spectra.