The Boys Choir of Kenya signed the deal in the transit lounge at London's Heathrow Airport as they returned home to Nairobi from Washington DC.
They were the only international choir to sing at the inauguration.
The choir, who are aged between 13 and 24, put on an impromptu performance for passengers before flying on to Kenya.
They have toured the US several times, and their performances have raised school fees for their members, as well as helping them take on several orphans.
Artistic director Joseph Muyale said: "We heard about the record deal about two days ago. I felt delighted on behalf of the boys.
"We began from humble beginnings and to be recognised by a large recording company is so humbling and quite an honour. We just thank God."
Universal Classics A&R representative Tom Lewis signed the contract at Heathrow Airport's Terminal 4.
He only saw the choir for the first time at the weekend, after a colleague advised him to watch a clip of them online.
Lewis said: "It has been frantic. I didn't know how I was going to get to see the choir - they're not allowed to leave the airport because they're in transit.
"At one point, I even considered buying a ticket so I could join them. But we've been allowed into the departures lounge."
He added: "I went onto YouTube and I saw their CNN performance and I thought, 'Wow - I do not want anyone else working with them.'"
The Boys Choir was formed in Nairobi in 1998 but expanded to members from outside the Kenyan capital in 2004. They now have 40 singers.
They were asked to sing at several events surrounding the inauguration of President Obama, whose father came from Kenya - although he never managed to see them perform.
The choir's repertoire includes a wide-ranging number of pieces from traditional Masaai and Samburu chants to contemporary songs from around Africa. They will now share a label with the likes of Amy Winehouse, U2 and The Rolling Stones.
Story from BBC NEWS:
Published: 2009/01/23 16:29:00 GMT
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