The original diploma was designed by Gerhard Munthe. The motif was inspired by the Norwegian lion, underlining the connection between the Nobel Committee and the Storting. The wording of the diploma also shows the link: "The Nobel Committee of the Norwegian Storting has, in accordance with the terms of the will set up by Alfred Nobel on the 27th of November 1895, awarded [name of laureate] the Nobel Peace Prize for [year]".

From 1970 up to and including 1990, the diploma was adorned with a woodcut by Ørnulf Ranheimsæter. In 1991 it was decided that the diploma should be given a new appearance each year by means of an original work of art commissioned from a contemporary Norwegian artist. Multicolour printing and calligraphy were adopted at the same time, replacing machine-printed lettering. The first diploma in the new format was the work of Karl Erik Harr. He has been followed by a number of well-known painters and graphic artists, including Håkon Bleken, Jakob Weidemann, Ørnulf Opdahl, Jens Johannessen, Franz Widerberg and Håkon Gullvåg.

The Nobel Artist for each year is now introduced to the public at an open house event held at the Nobel Peace Center on the day following the announcement of the award.