The moment The Rock FM's Roger Farrelly is told he's joined Dancing With the Stars NZ

Broadcaster Roger Farrelly was told he's joining this year's Dancing With The Stars NZ show live on air on Wednesday morning.

The Rock FM Morning Rumble host looked surprised as his co-hosts Andrew Mulligan and Bryce Casey gave him the news.

"You can't just come in and say that I'm on the show, surely - doesn't it start soon?" Farrelly exclaimed.

"[This is] a real shock!"

Farrelly said he'd been led to believe rugby star Richie McCaw was going to be the new announcement.

"You're basically a squintier Richie McCaw, who never went to the gym," joked Dai Henwood, a Dancing With the Stars NZ host who was in The Rock studio for the stunt.

"I don't know if you saw Simon Barnett's nipples last season, but I am pumped to see Roger's," added co-host Sharyn Casey.

Farrelly joins previously announced 2018 Dancing With The Stars NZ contestants David Seymour, Gilda Kirkpatrick, Marama Fox, Robbie Rakete, Jess Quinn and Chris Harris.

The show will debut on Three later this year.

Newshub.