Five's director of programmes, Jay Hunt, has been appointed as the controller of BBC One.
Jay Hunt's appointment follows the departure of Peter Fincham
She previously oversaw the BBC's daytime output and replaces Peter Fincham, who resigned in October.
Mr Fincham quit after being criticised by an inquiry into TV footage which wrongly implied the Queen had stormed out of a photoshoot "in a huff".
Ms Hunt, 40, said: "I could not resist the opportunity to take on such a creatively exciting role."
She added: "I am thrilled to be part of the channel's future.
"It has been an incredibly difficult decision to leave my talented team at Five but I could not turn down the best job in television."
JAY HUNT'S TV CAREER
1989 - Researcher, BBC Breakfast News
1998 - Senior producer, Panorama
1999 - Editor, One and Six O'Clock News
2002 - Executive producer, BBC Daytime
2005 - Controller, BBC Daytime
Sept 2007 - Director of programmes, Five
Dec 2007 - Controller, BBC One
Ms Hunt was appointed director of programmes at Five in September.
As the BBC's controller of daytime TV, she was responsible for all output on BBC One and Two during the day.
She commissioned factual programmes including Great British Menu, Extreme Dreams and Heir Hunters, and was also responsible for consumer shows such as Don't Get Done Get Dom and What's Really in Our Food?
Jana Bennett, the director of BBC Vision, welcomed Ms Hunt's appointment, saying she was "really pleased to welcome Jay back to the BBC".
"She has impeccable credentials as a commissioner, channel leader and journalist, and has a deep commitment to the BBC's mission to bring the best programmes to the widest audience."