The present disclosure provides a thin film transistor, a method of fabricating the same, an array substrate and a display device. The thin film transistor includes: source and drain electrodes in a same layer arranged on a base substrate; an active layer on the base substrate and in contact with the source and drain electrodes; a gate insulating layer at a side of the active layer away from the base substrate; a gate electrode at a side of the gate insulating layer away from the base substrate. Orthographic projections of the gate electrode, the source electrode and the drain electrode on the base substrate do not overlap with one another, and a region of the active layer not covered by the gate electrode, the source electrode and the drain electrode and at a side of the active layer away from the base substrate is subjected to conductorization.