Abstract: Metal-organic frameworks (MOFs)-based composites have been widely applied as photocatalysts because of their synergistic effect between the two individual component. Herein, TiO₂@NH₂-MIL-125(Ti) nanocomposites which possess unsaturated titanium–oxo clusters, mesoporous structure, and intimate interface were successfully constructed via an in-situ distilled water-etched route. The X-ray photoelectron spectroscopy (XPS) measurements indicated strong electronic interaction between TiO₂ and NH₂-MIL-125(Ti), confirming the formation of TiO₂@NH₂-MIL-125(Ti) nanocomposite. Photoelectrochemical and thermodynamics measurements showed that TiO₂@NH₂-MIL-125(Ti) nanocomposites have improved charge separation efficient and decreased transfer resistance of the carriers within the heterojunction interfaces, which facilitates the photoexcited electrons transfer and reduction of the Cr(VI) species. Therefore, the optimal TiO₂@NH₂-MIL-125(Ti) nanocomposite demonstrated superior performance compared to NH₂-MIL-125(Ti) and NH₂-MIL-125(Ti) derived TiO₂. Based on the free radical trapping experiment and electron paramagnetic resonance (EPR) measurements, a possible type-II scheme was proposed for the enhanced photocatalytic activity over the TiO₂@NH₂-MIL-125(Ti) nanocomposite.