The comedians are taking over from previous hosts Mel & Sue, as the cooking show controversially moves to Channel 4.
Sandi Toksvig, who also hosts QI and the C4 game show Fifteen to One, comments: "It is an extraordinary honour to part of this national treasure of a show. Noel Fielding is one of the nicest guys in show business. The first time I met him I felt like I had met a rather wayward cousin whose take on the world made me laugh. The only down side is that he has much better dress sense that I do. I spend my daytimes on Channel 4 already so it will be a treat to be there in the evenings. I am so delighted to be working with Love Productions and Channel 4 on this best of British show."
Channel 4 boss Jay Hunt says: "The Great British Bake Off will have a uniquely Channel 4 take when it airs this autumn. Paul and Prue have huge amounts of expertise and warmth. I'm looking forward to seeing them putting our great new bunch of amateur bakers through their paces. Sandi and Noel bring a fresh wit and quirkiness to the tent. It's just the sort of innovative lineup audiences expect from Channel 4."
Creator Richard McKerrow comments: "We are honoured to have the esteemed Prue Leith join Paul as judge on GBBO and know that Sandi and Noel will bring plenty of fun and warmth to the tent. We cannot wait for them to meet our new batch of bakers. On your marks, get set, BAKE!"
In other news, Paul O'Grady has been announced as the new host of Blind Date, for its new incarnation on Channel 5.
The Great British Bake Off will be on Channel 4 this autumn.