The metal band will join the previously announced Rammstein and Iron Maiden as the three main performers at the summer event.
They will headline the festival on June 14, 2013, marking their second headline slot at the event, having previously performed there in 2009.
Shawn Crahan said of the gig: "We are extremely honoured to have been asked once again to headline the Download Festival. This most definitely will be an experience not to be missed. Every time we've played Download we have created memories.
"It's always good to have the church of the Knot, the altar of the Knot, giving the sermon of the Knot to the congregation of the Knot, the culture of the Knot. This summer cannot come soon enough. Partake in the imagination or don't bitch."
Download organiser Andy Copping added: "Slipknot's last appearance at Download has gone down in the festival's history as one of the best ever headline sets. God knows what they'll have in store for 2013 but I'm looking forward to seeing how they'll top the last one."
The festival takes place on June 14-16 at Donington Park. Metallica, Black Sabbath and The Prodigy headlined this year's event.
Tickets for Download Festival will go on sale tomorrow (September 28) at 9am.
Slipknot revealed back in May that they plan to record a new album in 2013.
Watch the video for Slipknot's 'Vermillion' below: