The O2 event will raise funds for a trust set up in Stephen Lawrence's name to help young people from disadvantaged backgrounds.
Plan B, Jamie Cullum, Jessie J, Tinie Tempah and Ed Sheeran are also among the stars taking part in the show on September 29 designed to champion young people.
Stephen's mother, Doreen Lawrence, who founded the trust, said: "We work every day to empower youth and we're so proud that the music industry is joining us in reaching out to change the lives of young people.
"I want young people to feel inspired, be confident and have hope in their own future.
"There have been a further 106 racist murders since Stephen was killed 20 years ago and there are still too many young people who do not have a sense of hope."
Stephen was 18 when he was stabbed in a racist attack in Eltham, south east London, in April 1993. Two men - Gary Dobson and David Norris - were found guilty of the murder last year and the police investigation still remains "live".
The Metropolitan Police were criticised for their handling of the initial investigation and, as a result, the force was judged to be institutionally racist in a subsequent public inquiry.
The show, Unity: A Concert For Stephen Lawrence, has been backed by London Mayor Boris Johnson. Artists also include Rudimental and Soul II Soul.
Singer-turned-actor Plan B says that he's become a new man, after slimming down for his role as a flying squad officer in the film remake of The Sweeney.
The star, whose real name is Ben Drew, had to shed two stone before filming.
He told Men's Health Magazine: "losing the weight has changed my whole aura. When I walk into a room, I'm not paranoid about my weight any more, I'm just feeling a lot more comfortable and obviously that's an attractive thing in any human being."
Without losing the weight, he said, his performance in the cop drama would not have been believable:
"I needed to look like I could come through the door and arrest people, like I could compete with villains out there. The way I looked before, it just wasn't believable."