The band will headline the Friday night of the annual rock and metal weekend event, marking the third time they have topped the bill.
They will be supported by heavy metal bands Judas Priest and Five Finger Death Punch, while Kentucky rock band Black Stone Cherry will perform as 2nd stage headliners, reported Digital Spy.
Slipknot frontman Corey Taylor said of the announcement: "Being invited back to Download always feels like coming home. Headlining Download, for the third time, feels like the culmination of a life's dream. It's an honour, a privilege and we're all looking forward to it."
The 2014 festival was headlined by Avenged Sevenfold, Linkin Park and Aerosmith, and also saw acts including Fall Out Boy, Bowling for Soup, Steel Panther, The Pretty Reckless and Status Quo take to the stage.