When Tegnér was nine his father died, leaving the family without money. He received his schooling, however, because his talent was generally recognized. He graduated from the University of Lund in 1802 and was appointed professor of Greek there 10 years later. He continued to lecture at Lund until 1824, when he became bishop of Växjö, a position he retained all his life.

Originally associated with the Romantic movement, he rejected its emotional and mystic aspects. His ideal of poetry became increasingly more Classical but assimilated certain Romantic ingredients. His greatest poetic achievements were the much-translated Frithiofs saga (1825), a cycle based on an Old Icelandic saga, and two narrative poems, the sensitive religious idyll Children of the Lord's Supper (1820; translated by Henry Wadsworth Longfellow) and Axel (1822).

Tegnér, who had been a liberal most of his life, became an ultraroyalist in his later and rather unproductive years, during which he also showed signs of mental disorder.