Nick Grimshaw has been handed the flagship Radio 1 breakfast show after Chris Moyles announced on air that he was bowing out.
Grimshaw - who currently presents five night-time shows each week for the station - will take over in September.
Moyles, the longest-serving breakfast host in the station's 45-year history, shocked listeners with his departure but told them: "I've had the best time of my life."
Grimshaw, 27, has been with the station for five years and said he was "super excited" to be given the new role.
The presenter - known to listeners as "Grimmy" - said: "It's been a dream of mine since the age of 11 and, to be honest, it hasn't really sunk in yet.
"I love Chris and have always looked up to him as one of the best broadcasters ever."
The choice of Grimshaw will surprise many who had expected the role to go to fellow presenter Greg James, who hosts the drivetime show. He landed a regular show four years ago, hosting the weekend morning programme.
Radio 1 controller Ben Cooper said: "Nick is a great broadcaster with a passion for music and a mischievous sense of humour, which has made him a hit with our listeners.
"He will be an excellent host for Radio 1's new breakfast show, bringing a new generation of listeners with him."
Outgoing presenter Moyles is talking with bosses about a new programme for Radio 1 with which he is contracted until the end of next year. He was already due to take a break to appear as Herod in a touring version of Andrew Lloyd Webber's musical Jesus Christ Superstar.