Radio 1 DJs Fearne Cotton and Reggie Yates are taking over from JK and Joel to present the Sunday night chart show.
After three and a half years at the station, JK and Joel are leaving Radio 1 to concentrate on their TV careers.
They said: "We've got a variety of TV shows that we are filming at the moment - we'll now have more time for even more exciting new projects."
Fearne and Reggie will also host a new request show from 12 October as part of a big shake-up of what's on Radio 1.
Other changes include Kelly Osbourne joining the station as the new host of The Radio 1 Surgery, while DJ Chris Moyles will be starting his breakfast show 30 minutes earlier, at 6.30am.
There's also good news for fans of Dick and Dom - they've been given their own show on Sunday mornings.