Sandi Toksvig is leaving The Great British Bake Off as a presenter to focus on other work projects.
Toksvig presented the Channel 4 show with comedian Noel Fielding, alongside judges Paul Hollywood and Prue Leith, for three years.
They replaced duo Sue Perkins and Mel Giedroyc when the programme moved from BBC1. Hollywood is the only original star of the show after Mary Berry also left before the channel move.
In a statement the 61-year-old said: "When stepping down from a job it is quite common for people to say they are doing so in order to spend more time with their family.
"Unusually, I am departing from the Great British Bake Off so I can spend more time with my other work. As my waistline will testify, Bake Off is an all-consuming show.
"Spending time with Prue, Paul and Noel has been one of the great pleasures of my life. These are friendships which I know will continue beyond the confines of television.
"Bake Off is a wonderful programme which has already proved it can happily withstand a change of hosting personnel.
"The reason for that, of course, is that the true stars of the show are the bakers themselves. I wish everyone well."
Toksvig will be in the tent for The Great Celebrity Bake Off for Stand Up To Cancer which starts in the spring but it is not known who will replace her for the show later in the year.
Ian Katz, Channel 4's director of programmes, said: "Sandi is a huge part of why Bake Off's move to Channel 4 has been such a success and we are immensely grateful for her contribution to the show.
"We will miss her warmth and wit, not to mention her endless willingness to be the butt of jokes about being the least tall person in the Bake Off tent."
Her co-presenter Noel Fielding paid tribute to her on Twitter: "I feel like Tom without Jerry ! Mick without a Keef :( gonna miss yooooooooooooooooo and the wonderful times we got to play together in the tent ! Double acts are rare and magical beast and working with you was a pleasure x x x all my love Mr Noel x"
Bake Off judge Prue Leith tweeted: "I have absolutely loved working with Sandi, she's been a brilliant host and enormous fun and I am in awe of how hard she works juggling so many different projects.
"We shall be lifelong friends' way beyond the tent. #GBBO #sanditoksvig."
Toksvig, also known for hosting quiz shows QI and Fifteen To One, will host a new Channel 4 series called The Write Offs, which looks at the issue of adult literacy.