An array substrate, a method for manufacturing the same and a display device are provided. The method includes: providing a base substrate; forming a conductive material thin film on the base substrate; forming a first photoresist layer on a side of the conductive material thin film distal to the base substrate; etching the conductive material thin film by using the first photoresist layer as a mask to obtain a first etched pattern; removing third covering portions of the first photoresist layer to obtain a second photoresist layer; and etching the first etched pattern by using the second photoresist layer as a mask to obtain a gate electrode and a signal line.