A display panel and a producing method therefor, a vehicle-mounted rearview mirror, and a display device. The display panel comprises: a base substrate; a pixel defining layer, located at one side of the base substrate, the pixel defining layer comprising a plurality of openings distributed in an array; a cathode layer, located at the side of the pixel defining layer opposite to the base substrate; and an auxiliary cathode layer, located at the side of the cathode layer opposite to the pixel defining layer, the auxiliary cathode layer being directly in contact with and electrically connected to the cathode layer. The auxiliary cathode layer has a first thickness at positions corresponding to the plurality of the openings, and a second thickness at positions other than the openings; the first thickness is less than the second thickness.