Lönnroth gained his first degree at Uppsala University in 1961, and his PhD at Stockholm University in 1965.[2] He became associate professor in Scandinavian Studies at University of California, Berkeley in 1965, and professor in literature and text science at Aalborg University in 1974. From 1982 to 2000, he was professor in literary studies at the University of Gothenburg,[3] with a short break when he was Svenska Dagbladet's cultural director from 1991 to 1993. He was chairman of Statens konstnärsnämnd from 1995 to 2001, and chairman of Sällskapet Gnistan from 1999 to 2013.
Lönnroth's research has to a large extent dealt with the Icelandic medieval fairy tale literature. Together with Sven Delblanc, he was editor of the seven-volume work "Swedish Literature" (1987–90). He has written numerous other books including the 2005 Ljuva karneval! on Sweden's 18th century bard, Carl Michael Bellman. He has published his memoirs and a personal book about his family heritage from the nationalist poet, historian and composer Erik Gustav Geijer onwards, a legacy marked by the "poetry and madness" of the book's subtitle.[4]
Reviewing the Festschrift written in his honour in 2000,[5] Ulf Malm described Lönnroth as "the energetically combative and polemically gifted literature professor from Gothenburg".[6]
In Ljuva karneval!, written after some 40 years of research,[8] Lönnroth dispels the dominant 200 year old myth created by Johan Henric Kellgren that Bellman was always speaking for himself in his best-known work, Fredman's Epistles. The book explains that the reverse was the case; Bellman uninterruptedly played carefully-crafted roles,[7] including troubadour, court dramatist, and satirist.[9] The book presents Bellman as a skilful performance artist with an experimental, genre-crossing creativity.[10]Fredman's Epistles necessarily[8] take a central place in the book, but it offers much fresh detail on Bellman's lesser-known works, such as Bacchi Tempel.[8]
^Malm, Ulf. "Övriga recensioner"(PDF). Tidskrift för svensk litteraturvetenskaplig forskning. No. 12 February 2001. Svensk Litteratursällskapet. pp. 190–195. Retrieved 11 January 2021.
^"Extra Pris" (in Swedish). The Swedish Academy. 23 November 2016. Svenska Akademien har beslutat tilldela Lars Lönnroth ett extra pris på 100 000 kronor ur Akademiens egna medel.