Emma Willis is replacing Brian Dowling as the host of Big Brother.
Brian, 34, who won the reality TV show in 2001 and Ultimate Big Brother in 2010, has hosted the programme for two years, since it moved to Channel 5.
Emma, 37, who is married to former Busted star Matt, is the host of spin-off show Big Brother's Bit On The Side.
The presenter, who will also front Celebrity Big Brother, said: "I am thrilled to have been offered this job.
"I'm a fan first and foremost so to be able to front the show is going to be amazing. Roll on the summer!"
Channel 5 director of programmes Ben Frow said: "Emma is a natural on screen, she's made the spin-off show her own and now the time is totally right for her to step up.
"I know she'll take Big Brother to the next level and I can't wait to see her dealing with the housemates both famous and soon- to-be famous.
"I'd also like to thank Brian Dowling for doing such a sterling job over the last two years. He's been a big part of the success of the show and I wish him the very best."
Reports had previously suggested that Emma was in talks for the role, and that she was seen by channel chiefs as a true successor to Davina McCall.
The show will return this summer.