This was lying unattended with a collection of other Middle Eastern books and documents, without being identified as one of the oldest fragments of the Quran in the world.
The pages of the manuscript had remained unrecognised in the university library for almost a century.
The discovery of Quran is exciting and will make Muslims rejoice," Dr Muhammad Isa Waley, the British Library's expert on such manuscripts.
The university's director of special collections, Susan Worrall, said researchers had not expected "in our wildest dreams" that it would be so old.
The radiocarbon dating test was carried out after a PhD researcher, Alba Fedeli, looked more closely at these pages.
The fragments were written on sheep or goat skin, were among the very oldest surviving texts of the Quran, according to Oxford University Radiocarbon Accelerator Unit which carried out the test.