The three-day event, which is held in London's Victoria Park, is to be headlined by The Wombats, Snoop Dogg and Scissor Sisters.
Jessie J is to play the main stage on Saturday, while Beth Ditto will appear on the Sunday.
Other acts added to the bill include Santigold, The Joy Formidable and Cherryghost.
Lovebox is to be held between July 15 and July 17.
Tickets for the festival are on sale now.
Watch the video for Jessie J's 'Price Tag' below.