After studying at Uppsala, Almqvist entered the Department of Ecclesiastical Affairs in Stockholm. In 1823 he gave up his position and went to western Sweden to lead with a group of friends an idealized peasant existence patterned after the ideas of Rousseau. Two years later he returned to Stockholm, and from 1829 to 1841 was principal of an experimental secondary school. In 1851 he fled to the U.S. after being accused of fraud and the attempted murder of a moneylender. He returned to Europe in 1865.

Almqvist was little known until the mid-1830s when he began to publish a stream of works in prose and verse. Most of these—novels, short stories, poems, and verse dramas—were included in a series called Törnrosens bok (“The Book of the Briar Rose”; 13 vol., 1832–40; vol. 14, 1851; 2nd series, 1839–50). Particularly important were Amorina (written c. 1821; rewritten and published 1839) and Drottningens juvelsmycke (1834; “The Queen's Diamond Ornament”), a historical novel whose heroine, the mysterious, hermaphroditic Tintomara, is Almqvist's most fascinating character and a central symbol in his creative writings. Det går an (1838; Sara Videbeck, 1919) is a brilliant, realistic story pleading for the emancipation of love and marriage. The work foreshadows Strindberg's method of raising problems for debate. He was also a musician and set some of his short lyrics to music.

Almqvist showed an astonishing versatility. He attacked conventional matrimony, satirized the beliefs of the Lutheran Church (although he was ordained in 1837), and as a journalist and in many of his creative writings fought for moral and social reform. But he had strong tendencies toward egocentric aloofness, and the core of his personality remained dominated by Christian mysticism and Swedenborgian otherworldliness.