The Australian singers will search for ex-pat talent in London following news that the show is to hold auditions in the UK and US for the first time.
They will join forces with judge Ian 'Dicko' Dickson and co-host James Matheson, who will fly to London tomorrow to help find potential contestants.
The decision to audition further afield follows the success of Perth-born Michael Johns, who finished in the top ten on American Idol. It is hoped the format change will boost flagging ratings, which reached an all-time low in the last season.
Hayes, former frontman of band Savage Garden, told Confidential: "As an Australian entertainer living in London I definitely have a soft spot for Aussies trying to make it overseas. Rather than judging people, I'm going to be looking for that little bit of magic that someone once saw in me.
"I think potential is a huge criteria for a musical career and hopefully Tina and I can help discover some. I love Dicko and Tina so I'm sure I'm going to have a blast."