The manuscript, which was called by Sotheby's vice chairman David Redden 'the birth certificate of freedom,' was bought by David Rubenstein, the founder of the Carlyle Group, a global private equity investment company.
Magna Carta, which proclaims personal freedoms and the rule of law, is considered the historical inspiration for documents such as the U.S. constitution and the Bill of Rights.
The document, written in Latin on vellum and bearing the wax seal of King Edward I, is the last original in private hands, and earlier belonged to Texas software billionaire Ross Perot, who acquired it in 1984 for $1.5 million.
The document was said by the auction house to be in remarkable condition for its age.
The manuscript's new owner said he was just a 'temporary custodian' and would hand it back to the U.S. National Archives in Washington, where it had been displayed since 1988.
The Perot Fund will allocate the money it raised from selling the charter to medical research, the treatment of soldiers wounded in Iraq, and education projects.
