Skepta, Misha B and a DJ set from Foals are also added to the London bash's bill
The event takes place in Victoria Park, east London, on August 31, having moved to a much later date this summer to accommodate the London 2012 Olympics.
The rapper, who releases his second studio album ‘A Moving Picture’ in October, is among four new additions to the festival, with Skepta, former X-Factor contestant Misha B and a DJ set from Foals also added by the event’s organisers.
They join a bill that already includes Spector, Fixers, Summer Camp, Pulled Apart By Horses, Iceage, Theme Park, Rustie, BIGKids, Maverick Sabre and Dry The River. More acts will be confirmed in the coming weeks.
To attend the festival, ticket-holders must be under the age of 18, but over 13. See Underagefestivals.com for more information.
The Underage Festival line-up so far is as follows:
Dry The River
Foals (DJ Set)
Lianne La Havas
Pulled Apart By Horses