His father was a pastor, and his grandparents on both sides were peasants. His father, whose name had been Esaias Lucasson, took the surname of Tegnérus — altered by his fifth son, the poet, to Tegnér — from the village of Tegnaby in the province of Småland, where he was born. In 1792 Tegnérus died.

In 1799 Esaias Tegnér, hitherto educated in the country, entered Lund University, where he graduated in philosophy in 1802, and continued as tutor until 1810, when he was elected Greek lecturer. In 1806 he married Anna Maria Gustava Myhrman, to whom he had been attached since his earliest youth. In 1812 he was named professor, and continued to work as a lectuer in Lund until 1824, when he was made bishop of Växjö. At Växjö he remained until his death, twenty-two years later.

Tegnér's early poems have little merit. He was comparatively slow in development. His first great success was a dithyrambic war song for the army of 1808, which stirred every Swedish heart. In 1811 his patriotic poem Svea won the great prize of the Swedish Academy, and made him famous. In the same year was founded in Stockholm the Gothic League (Götiska förbundet), a sort of club of young and patriotic men of letters, of whom Tegnér quickly became the chief. The club published a magazine, entitled Iduna, in which it printed a great deal of excellent poetry, and ventilated its views, particularly as regards the study of old Icelandic literature and history. Tegnér, Geijer, Afzelius, and Nicander became the most famous members of the Gothic League.

The majority of the many poems from Tegnér in his little room in Lund are short, but some are in lyrics. They are today shown to visitors at the Tegnér museum. His celebrated Song to the Sun dates from 1817. He completed three poems of a more ambitious character, on which his fame chiefly rests. Of these, two, the romance of Axel (1822) and the delicately chiselled idyl of Nattvardsbarnen ("The First Communion," 1820), translated by Longfellow, take a secondary place in comparison with Tegnér's masterpiece, of worldwide fame.

In 1819 he also became a member of the distinguished Swedish Academy, on seat 8.

In 1820 he published in Iduna fragments of an epic on which he was working: Frithjof's saga (The Story of Frithiof). In 1822 he published five more cantos, and in 1825 the entire poem. Already before its last canto it was famous throughout Europe; the aged Goethe took up his pen to commend to his countrymen this "alte, kräftige, gigantischbarbarische Dichtart," and desired Amalie von Imhoff to translate it into German. This romantic paraphrase of an ancient saga was composed in twenty - four cantos, all differing in verse form, modelled somewhat, it is only fair to say, on an earlier Danish masterpiece, the Helge of Oehlenschläger.

Frithjof's saga was during the 19th century the best known of all Swedish productions; it is said to have been translated twenty - two times into English, twenty times into German, and once at least into every European language. It is far from satisfying the demands of more recent antiquarian research, but it still is allowed to give the freshest existing impression, in imaginative form, of life in early Scandinavia. In later years Tegnér began, but left unfinished, two important epical poems, Gerda and Kronbruden.

The period of the publication of Frithjof's saga (1825) was the critical epoch of his career. It made him one of the most famous poets in Europe; it transferred him from his study in Lund to the bishop's palace in Växjö; it marked the first breakdown of his health, which had hitherto been excellent; and it witnessed a singular moral crisis in the inner history of the poet, about which much has been written, but of which little is known. Tegnér was at this time passionately in love with a certain beautiful Euphrosyne Palm, the wife of a town councillor in Lund, and this unfortunate passion, while it inspired much of his finest poetry, turned the poet's blood to gall. From this time forward the heartlessness of woman is one of Tegnér's principal themes.

It is a remarkable sign of the condition of Sweden at that time that a man without a Christian heritage, and of little interest in religious matters, should be offered and should accept a bishop's crosier. He did not hesitate in accepting it: it was a great honour; he was poor; and he was anxious to get away from Lund. No sooner, however, had he begun to study for his new duties than he began to regret the step he had taken. It was nevertheless too late to go back, and Tegnér made a respectable bishop as long as his health lasted. In 1835, he was elected a member of the Royal Swedish Academy of Sciences. But he became moody and melancholy; as early as 1833 he complained of fiery heats in his brain, and in 1840, during a visit to Stockholm, he suddenly became insane.

He was sent to an asylum in Schleswig, and early in 1841 he was cured, and able to return to Växjö. It was during his convalescence in Schleswig that he composed Kronbruden. He wrote no more of importance; in 1843 he had a stroke of apoplexy, and on 2 November 1846 he died in Växjö.