Radiocarbon dating found the manuscript to be at least 1,370 years old, making it among the earliest in existence.
The pages of the Muslim holy text had remained unrecognised in the university library for almost a century.
The British Library's expert on such manuscripts, Dr Muhammad Isa Waley, said this "exciting discovery" would make Muslims "rejoice".
The manuscript had been kept with a collection of other Middle Eastern books and documents, without being identified as one of the oldest fragments of the Koran in the world.
"They could well take us back to within a few years of the actual founding of Islam," said David Thomas, the university's professor of Christianity and Islam.
"According to Muslim tradition, the Prophet Muhammad received the revelations that form the Koran, the scripture of Islam, between the years 610 and 632, the year of his death."
Prof Thomas says the dating of the Birmingham folios would mean it was quite possible that the person who had written them would have been alive at the time of the Prophet Muhammad.
