GMTV presenter Penny Smith is quitting the ITV breakfast programme after 17 years, the show has confirmed.
The announcement comes amid plans to revamp the morning show.
"It's an ideal time for me to say goodbye to early mornings. Now that the format has changed, I have taken the plunge and am moving on," said Smith.
Smith, 51, will host a new BBC Radio 2 opera show in June and is working on her third novel. She is also said to be in talks with ITV about other projects.
"Penny has been a welcoming and familiar face on Britain's breakfast screens for many years," said GMTV's managing editor Neil Thompson.
"She has become a hallmark of GMTV's presentation, not only on the sofa but also as a newsreader.
"She has done a fantastic job over the last 17 years and has made an enormous contribution to the success of the News Hour.
Mr Thompson said the team were "taking a fresh look at the editorial direction of the entire show".
He added that they needed to "ensure that our news really punches through and offers viewers a distinctive and authoritative take on the big stories of the day, whenever and wherever they happen".
Smith's co-host John Stapleton has been appointed the show's first special correspondent.
His new role will see him go on the road to "bring viewers his inimitable eye-witness accounts of the major national and international stories".
He said: "I'm going back to doing what I love best - covering major national and international news stories, and, after 12 years of getting up at 3.45am, I'm looking forward to having at least a few lie-ins a week when I'm not on duty."