Ed Sheeran, Mary J. Blige and Jessie J have been added to the iTunes Festival line-up.
The 'Sing' hitmaker has been announced to perform at the month-long series of gigs at The Roundhouse in Camden, north London, on September 29.
'Bang Bang' singer Jessie will perform on September 22 and US R&B star Mary will headline the September 25th show.
The trio join previously announced headliners Maroon 5, Sam Smith, Calvin Harris, Pharrell Williams and Kylie Minogue.
Ed said: "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."
Mary added: "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."
US crooner Tony Bennett - who is due to release an album with Lady Gaga - has also been announced for the festivities.
He commented: "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!"
iTunes Festival 2014 line-up:
September 1 - deadmau5
September 2 - Beck and Jenny Lewis
September 3 - David Guetta, Clean Bandit and Robin Schulz
September 4 - 5 Seconds of Summer and Charlie Simpson
September 5 - Kasabian
September 6 - Tony Bennett
September 7 - Calvin Harris and Kiesza
September 8 - Robert Plant and Luke Sital-Singh
September 9 - Sam Smith and SOHN
September 10 - Pharrell Williams and Jungle
September 11 - Maroon 5, Matthew Koma and Nick Gardner
September 12 - Elbow and Nick Mulvey
September 13 - Paolo Nutini and Rae Morris
September 14 - David Gray and Lisa Hannigan
September 15 - The Script and Foxes
September 16 - Blondie and Chrissie Hynde
September 17 - Gregory Porter and Eric Whitacre
September 18 - Jessie Ware and Little Dragon
September 20 - Rudimental and Jess Glynne
September 21 - Ryan Adams and First Aid Kit
September 22 - Jessie J and James Bay
September 23 - Placebo
September 24 - Ben Howard and Hozier
September 25 - Mary J. Blige
September 26 - Lenny Kravitz and Wolf Alice
September 27 - Kylie and MNEK
September 28 - Nicola Benedetti, Miloš and Alison Balsom
September 29 - Ed Sheeran and Foy Vance