We investigated the electronic reconstruction at the n-type LaAlO₃/SrTiO₃ interface with hardx-ray photoelectron spectroscopy (HAXPES) under grazing incidence. By exploiting the collapseof evanescent x-ray waves and the abrupt increase of x-ray absorption at the critical incidenceangle, our HAXPES study reveals a 2% electronic reconstruction from Ti⁴⁺ to Ti³⁺ occurring nearthe interface. Such an electronic reconstruction also extends from the interface into SrTiO₃ with adepth of about 48 (~12 unit cells) and an estimated total charge transfer of ~0.24 electrons pertwo-dimensional unit cell.