The singer will perform her most popular hits at Weston-super-Mare on July 1, including material from her chart-topping second album Electra Heart.
The star joins a lineup which already boasts sets from Little Mix, The Wanted, Tulisa, Dappy, Cover Drive, Alexandra Burke, Labrinth, Professor Green and Rizzle Kicks.
Newcomers Conor Maynard and Rita Ora will also perform, along with Maverick Sabre and Wretch 32.
T4 presenters Jameela Jamil, Nick Grimshaw, Georgie Okell, Matt Edmondson and Will Best will host the event, which will also include appearances from the cast of Made in Chelsea.
Tickets for this year's T4 On The Beach are on sale now.
Watch highlights from the past ten years of T4 On The Beach below: