An array substrate, a method for fabricating the array substrate and a display panel. The array substrate is provided with at least one isolation mesa in each of multiple pixel grooves in a pixel-defining layer, so that a light-emitting layer of a second sub-pixel located on the isolation mesa and a light-emitting layer of a first sub-pixel located on an exposed portion of a bottom surface of the pixel groove are on different planes and thereby isolated. It is prevented that an adjacent sub-pixel is influenced via the light-emitting layer, in a case that the anode of the second sub-pixel and the anode of the first sub-pixel receive different voltages. The isolation mesa does not form a non-emitting region in the pixel groove. An aperture ratio of the array substrate is not reduced. High PPI of the array substrate is ensured.