Academics believe the lost manuscripts, including correspondence between the national Bard and close friends, throw significant new light on his life and work, and are said to be among the most important Burns finds in recent years.
The documents will be presented today at the University of Glasgow Burns Conference.
The documents were identified by Chris Rollie, a Burns expert based in Dalry in Dumfries and Galloway, after being told by a contact about a private collection.
He examined the cache, and found three handwritten manuscripts by Burns, three letters to the Bard, and a tender letter from his famous lover Clarinda McLehose to his physician, Dr William Maxwell, asking details of how the poet died.
The collection had been lost to scholars for almost 200 years until Mr Rollie found them in 2010.
Mr Rollie said: "I realised very quickly that the material I was looking at was original and felt that some of it might be unpublished.
"Careful research revealed that, while some of the material had been previously published, it was long lost, and some material was indeed new to Burns scholarship.
"I feel very privileged to have discovered these manuscripts."
The documents include a hand-written manuscript of Burns's Phillis The Fair.
There is a draft of Ode To A Woodlark, published in 1877-79 but since lost, and a handwritten letter from Burns to Robert Muir of Kilmarnock, first published in 1834 but missing since then.
A letter from McLehose to Burns, dated 1791 and published in part around 1878, has also been recovered. The previously unpublished letter from her to Dr Maxwell is dated October 31, 1796, just over three months after Burns's death.
There is a letter to Burns by George Thomson, one of his publishers, from 1793, a manuscript that was lost until now. The newly discovered Epistle to Burns by Andrew Hunter Aiken, sent to Burns in 1793, is thought to have never been published.
Professor Gerry Carruthers, co-director of the university's Centre for Robert Burns Studies, said: "The finding of the Clarinda letter in full is very timely as we move towards a new edition of Burns's correspondence, and the other new manuscript findings of letters will also help."