John Summit, Jennie, The Smashing Pumpkins, Geese, Wet Leg, Yungblud and Wolf Alice will also play the Chicago festival
Others added to the line-up include Myles Smith, Ezra Collective, Holly Humberstone and Alessi Rose
Others on the guestlist included Jacob Alon, Dave, Holly Humberstone, Self Esteem, Jeff Goldblum, Bez, and Ezra Collective
Bookmakers have slashed odds after her success at the BRIT awards
She took home Album of the Year, Song of the Year, Artist of the Year and Best Pop Act
The actor and comedian tells NME about returning to host for a record-breaking sixth time, why he doesn't "shit the bed quite as much as I used to" while keeping it spicy, and being a "kindred spirit" with Harry Styles
She joins an impressive list of previous ambassadors including Taylor Swift, Kate Bush, Noel Gallagher and Elton John
They join Olivia Dean, FLO and Tiwa Savage on the line-up for the March 26 awards show
Dean is up for five awards at this year's ceremony, which is being held outside of London for the first time in its 50-year history
Fender and Olivia Dean's 'Rein Me In' has beaten a record held by Ed Sheeran since 2014