The book, Codex Sinaiticus, is thought to be one of the world's most important written pieces and has only been lent out once, in 1990, again to the British Museum.
Elisabeth O'Connell, Assistant Keeper in the Ancient Egypt and Sudan department, said: "It's quite phenomenal that they are able to lend it to us.
"We are absolutely thrilled," she said in The Guardian.
The book dates back to the fourth century AD and is handwritten in Greek.
It is thought to contain the earliest manuscript of the New Testament and was written after the reign of Emperor Constantine the Great.
It was bought from the Soviet Russian leader Joseph Stalin, in 1933, when the country needed money.
Scot McKendrick, Head of Western Manuscripts at the British Library, said: "Since it arrived in the 1930's it has always been one of the greatest treasures in the collection."
He said it was paid for using £100,000 raised by public subscription at the time, "It was an amazing achievement given the circumstances," he added.
There are around 27,000 corrections in the Codex.
Mr McKendrick said: "This is a very beautiful and fine book, but it also has all this activity going on in the margins and between lines, all over the place really."
Experts on the book think it was compiled by four scribes and was used as the skeleton for every Christian Bible.
It will be displayed in the British Museum alongside two other texts of the Hebrew and Muslim faiths, looking at how these original religious texts have helped shaped the modern world.
