Ed Sheeran and Mary J Blige are amongst the latest additions for the 2014 iTunes festival.
Singer-songwriter Ed, whose latest album X topped the UK charts, will take to the stage at Camden's Roundhouse on September 29.
"I'm very happy to be playing my third iTunes festival next month. I first played supporting Bruno Mars in 2011 and then came back the next year for my own," he said.
Soul star Mary will make her debut on September 25 at the month-long event, which kicks off on September 1 and runs throughout the month.
"I'm so happy to be playing for my first time at iTunes festival. I've always loved visiting London and I can't wait to be back to see my UK fans next month," she said.
Other acts who have joined the bill include Jessie J, Tony Bennett, Placebo, Ben Howard and Nicola Benedetti, with Canadian musician Deadmau5 opening the festival.
Tony, who is releasing a new duets album with Lady Gaga, said: "I'm thrilled to be back at iTunes festival once again. It's a phenomenal musical experience for both the performers and the audience and I love being part of it!"
Ben added: "Delighted to be performing at iTunes festival for the first time; the Roundhouse is such a historic venue, it's an honour. Looking forward to playing tunes from my new album, I Forget Where We Were. Should be a fun night!"
Previously announced names on the 60-strong line-up include Pharrell Williams, Kylie Minogue, Beck, Kasabian, Elbow, Calvin Harris, Robert Plant and Sam Smith.
The shows, which are free to UK residents, will be streamed live on iTunes. See www.itunes.com/festival for further details.