The duo will become the brand new hosts of Sunday mornings on Heart, presenting to an audience of more than nine million listeners.
Caroline and Gethin will start their new roles this week, every Sunday morning on Heart from 9am to 12pm, while Stephen Mulhern and Emma Willis take a break.
This is Caroline's first job since hosting The X Factor last year with Olly Murs. It's set to be a busy summer for Caroline, as the 2014 Strictly Come Dancing champion will also be returning to Majorca to film the second series of revamped dating show Love Island.
Caroline said: "Sunday mornings are the perfect time for listening to feel good tunes and having fun, and I've always wanted to work in radio so I'm incredibly excited about our new show on Heart."
Meanwhile, Blue Peter star and former Dancing with the Stars: All Access host Gethin added: "Heart has a brilliant presenter line-up and I'm thrilled to be joining the team with Caroline. It's great to be back on the radio and I know we're going to have a lot of fun with our listeners."
It was first reported last month that Caroline had been offered the radio presenting gig, with producers apparently hoping to make it a permanent stint.
Gary Stein, managing editor of Heart, said: "Gethin and Caroline are two of the country's most popular presenters so I'm delighted they've chosen to join Heart. There's a brilliant chemistry between the two of them and I know their energy and charisma will bring a real feel good vibe to Sunday mornings on Heart."
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