They will be headlining the event on June 10 at the Dreamland theme park in Margate.
The full line-up is yet to be announced.
Earlier this year, the band debuted new material by releasing an anti-Donald Trump song called ‘Hallelujah Money’ featuring Benjamin Clementine.
Albarn and Hewlett have been working on a new album for the past two years.
Hewlett told a fan last year that the LP was ‘really fuckin’ special’ and ‘can’t be rushed’.
The band’s last album, The Fall, came out in 2011.
Tickets for Demon Dayz Festival go on sale at 9am on Friday, March 10 and will be available from the official website here.