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.