The present application provides a thin film transistor (TFT) and a method of fabricating the same, a display substrate and a method of fabricating the same, and a display device. The TFT includes a substrate, and a source electrode, a drain electrode and an active layer on the substrate. The active layer includes first and second active layers, the first active layer has a carrier mobility greater than that of the second active layer, and the second active layer is closer to the source electrode and the drain electrode than the first active layer. An orthographic projection of the source electrode on the substrate and an orthographic projection of the drain electrode on the substrate at least partially overlap with an orthographic projection of the second active layer on the substrate, respectively, and the first active layer is separated from the source electrode and the drain electrode.