After studying for four years at Copenhagen University, under the Danish philologist Rasmus Christian Rask, he returned to England in 1830, and in 1832 published an English version of Caedmon's metrical paraphrase of portions of the Holy Scriptures, which at once established his reputation as an Anglo-Saxon scholar.

Thorpe died at Chiswick in July 1870. The value of his work was recognized by the grant to him, in 1835, of a civil list pension.

In 1834 he published Analecta Anglo-Saxonica, which was for many years the standard textbook of Anglo-Saxon in English, but his best-known work is a Northern Mythology in three volumes (1851). His was the first complete good translation of the Elder Edda (1866).

His other works include:

• Ancient Laws and Institutes of England (1840), an English translation of the laws enacted under the Anglo-Saxon kings
• The Holy Gospels in Anglo-Saxon (1842)
• Codex Exoniensis (1842), a collection of Anglo-Saxon poetry with English translation
• an English translation of Dr Lappenburg's History of England under the Anglo-Saxon Kings (1845)
• Anglo-Saxon Poems of Beowulf (1855), a translation
• an edition for the Rolls Series of the Anglo-Saxon Chronicle (1861)
• Diplomatarium Anglicum aevi saxonici (1865), a collection of early English charters.