His estate has signed a deal with HarperCollins to release it as a book in May, accompanied by further thoughts on the text which he prepared for a series of lectures given at Oxford during his academic career.
The new work, Beowulf: A Translation and Commnetary, has been edited by his son Christopher Tolkien.
It is the latest in a series of posthumous publications for the author, who died in 1973 and is best known for his fantasy works including The Hobbit.
Last year his poem The Fall of Arthur was published for the first time.
Christopher Tolkien said: "The translation of Beowulf by JRR Tolkien was an early work, very distinctive in its mode, completed in 1926. He returned to it later to make hasty corrections, but seems never to have considered its publication.
"This edition is twofold, for there exists an illuminating commentary on the text of the poem by the translator himself, in the written form of a series of lectures given at Oxford in the 1930s."