Guðni Jónsson (22 July 1901 – 4 March 1974) was an Icelandic professor of history and editor of Old Norse texts.
He was raised by relatives at Leirubakki until he was twelve, worked two seasons as a fisherman and then was taken in by his married sister in Reykjavík, enabling him to attend evening school there.
He completed a master's degree in Icelandic studies in 1930 with a thesis on Landnámabók, comparing the manuscripts with each other and with other texts.
His doctoral thesis, published in 1952, was in genealogy and history: Bólstaðir og búendur í Stokkseyrarhreppi.
He also published histories of the Flensburg school (1932), the Eimskipafélag Íslands shipping company (1939) and the University of Iceland (1961).