The wildly popular music artists are collaborators on the current hit song "Suit & Tie."
This will be Timberlake's only U.K. festival performance of the year.
"So this is your one chance to see him in a festival setting in 2013, performing songs from his new album, 'The 20/20 Experience,'" a message on his website said.
Jay-Z will be the headlining act at the London festival July 13. Set to take the stage that day as well are Emeli Sande, Rita Ora, Calvin Harris and Kendrick Lamar.
Jay-Z and Timberlake announced Friday they are planning a North American stadium concert tour together this summer.
Their "Legends of the Summer" show will stop in 12 cities, including New York, Boston, San Francisco, Los Angeles, Chicago and Toronto.