Lionel Richie and Duran Duran are also on the bill at the star-studded event due to run from June 30 to July 4 next year.
The band are partnering with the UK's Trussell Trust for the EP and all proceeds from the project will go to the anti-poverty charity.
The track will also feature on the band's new EP, ‘The Fireside Sessions’ set for release on August 21.
Next year's festival will run from July 22-25, 2021 at the event’s usual Suffolk location of Henham Park.
Snow Patrol and Duran Duran, also previously scheduled as 2020 headliners, will again feature on next year’s bill.
The Scottish rock band from Dundee led by Gary Lightbody are known for their emotionally charged songwriting and passionate fanbase.
KISS, Iron Maiden and System Of A Down were due to headline Download, while the Isle Of Wight was set to host Lewis Capaldi, The Chemical Brothers and Lionel Richie.
Other big names on the bill include Run The Jewels, Rick Astley and The Stone Roses' Ian Brown.
Other winners on the list include Snow Patrol's Gary Lightbody and Olivia Newton-John.
The iconic UK festival will return once between 11 and 14 June, with the above acts topping the bill across the entire weekend.
The record accompanies a ‘Reworked’ tour starting on 13 November through to 5 December
The 'Reworked' tour touches down in cities including London, Oxford, Dublin, and Belfast.
The new release also includes 'Time Won't Go Slowly' and new versions of ‘Open Your Eyes’ & ‘Chocolate’.
The original recording of the track featured on Snow Patrol’s 2008 album, 'A Hundred Million Suns.'
Singer Gary Lightbody has described the track as “the purest love song” he has ever written.
