London rapper Professor Green and The Saturdays have also been announced to play the event, which is held in Weston-super-Mare.
The gig marks Green and Vickers's debut at the beach festival, which is now in its eighth year.
They join a long list of already confirmed acts including JLS, Alexandra Burke, Pixie Lott and Chipmunk.
This year's T4 On The Beach takes place on July 4. Tickets are on sale now.