Jay-Z to headline Hackney Weekend
Jay-Z is to headline BBC Radio 1's Olympic celebration, the Hackney Weekend 2012
The rap superstar - who has previously topped the bill at Glastonbury - will have the main slot on June 23 at the free event at east London's Hackney Marshes.
Jay-Z, who recently became a father after his wife Beyonce gave birth to daughter Blue Ivy, joins stars such as Tinie Tempah, Jessie J and Ed Sheeran who have already been announced for the shows.
Another headliner for the second night - June 24 - will be announced over the coming weeks.
The station is giving away 100,000 tickets to listeners for the event which will feature 100 acts performing on six stages.
Registration for ticket applications continues until March 19 at bbc.co.uk/radio1, although most places will be reserved for people who live in the London boroughs close to the Olympic site.
Also due to perform are Emeli Sande, Florence and the Machine, Jack White and Lana Del Rey.
Jason Carter, event director for the weekend, said: "Our goal was to deliver the most ambitious and exciting event in Radio 1's history and with the artists already announced I think we've achieved that, but to now add the world's biggest hip hop icon, Jay-Z, to the line-up, is fantastic news.
BBC3 will also screen the event.