The present study addresses the quantitative estimation and understanding of the nature of phases present in Mo-incorporated titania through extensive EXAFS measurements (at Mo K-edge and Ti K-edge) and to decipher their role in photodegradation of Methylene Blue (MB) dye under UV and visible irradiation. EXAFS results revealed the presence of both MoO₃ nano heterophase phase and substitutional Mo dopants in the TiO₂ lattice, the extent of the latter was reduced with the increasing Mo content of the sample. The presence of MoO₃ in the Mo-incorporated titania was also revealed by FT-IR and TEM studies. Photocatalytic studies have shown considerable adsorption of the cationic MB-dye, perhaps due to the electronic interaction between the dye and catalytic surface. Under visible irradiation, the photocatalytic activity followed the trend: Mo-5 > Mo-2 > Mo-1 > Mo-10 ≫ TiO₂, while the trend for photodegradation of MB dye under UV irradiation was as follows: Mo-5 > Mo-2 > Mo-1 > TiO₂ > Mo-10. These results have been explained in the light of the structural properties of the Mo–TiO₂ system obtained from EXAFS measurements. It has been observed that the relative ratio of substitutional Mo-dopant to the MoO₃ phase in this tri-phasic photocatalyst plays a crucial role in augmenting its oxidative photocatalytic property.