The ebooks, which are all works from the 19th century, will include titles by Charles Dickens, Jane Austen and Thomas Hardy and will be available for download this spring.
Microsoft and the British Library have been digitising the books for the past three years and have been concentrating on 19th century works because they are out of copyright and can legitimately be offered for free.
Amazon Kindle owners will be able to get their hands on free eBooks from the British Library this spring
The British Library also revealed that around 35 to 40 percent of its 19th century books, all of which have now been digitised, can not be found in other public libraries and are unlikely to be found for sale in second hand bookshops or online.
Web users will also be able to order printed copies of these works from Amazon for around £15 to £20 each. The printed version will include the original typefaces and illustrations.
"Freeing historic books from the shelves has the potential to revolutionise access to the world's greatest library resources," said Lynne Brindley, chief executive of the British Library.
The library also revealed it hopes to digitise books from the 20th century as well, but funding for this portion of the project has yet to be found.