The 52-year-old first presented the flagship morning show in 2001 and moved with the famous red sofa to Media City in Salford as a lead presenter in 2012.
WATCH: Louise Minchin tearfully confirms BBC Breakfast exit
Speaking about her decision on Tuesday, Louise said: "I have absolutely loved being part of the 6 million-strong BBC Breakfast family but after nearly two decades presenting the programme, I have decided it is time I stopped setting my alarm for 03.40 in the morning.
"I will take so many memories with me, including reporting on the shock and anguish of the Manchester Arena bombing; starting a national conversation about Menopause; and the life-changing moment I took part in the Breakfast Christmas Cycling Challenge which inspired my ongoing passion for endurance sport, which I will continue when I leave."
She concluded: "A big thank you to everyone who has watched and supported me, I have loved it and I will miss you all."
Louise announced her exit news on Tuesday morning
On the show a tearful Louise told viewers: "Let me take a deep breath, everybody there is something I want to tell you about. It will be this year 20 years since I first presented this programme. Since then I've felt part of a huge, enormous BBC Breakfast family which includes everyone who works here, everyone on the team and every one of you who watches the programme.
"I've loved being part of it but - there is a but - I've decided that is time that I stop setting my alarm for 3.40 - sometimes if I'm feeling really rebellious 3.46 - in the morning and I'm going to be leaving the programme."
Confirming she will leave later this year, the broadcaster added: "It's not going to be for a while. But before anything else I wanted to thank everyone that is watching for your loyalty and your support over all those years. I have absolutely loved being part of it and I will really miss it, but it's time now to stop that alarm early in the morning. And thank you for watching for all these years."
Her co-host, Dan Walker, later tweeted: "As with everything she does... Louise announces her departure from the show with dignity and class. We will all miss her enormously at #BBCBreakfast."
He added: "She is not only wonderful at her job... she is a great friend. Enjoy your lie-ins @louiseminchin."
The TV star uploaded this photo with her co-host Dan Walker ahead of the surprise announcement
During her time on BBC Breakfast, Louise has reported on major global news stories from the last two decades, including the last three general elections, Brexit, the worldwide COVID-19 pandemic, the Manchester Arena bombings and the aftermath of the Bataclan Theatre attacks, live from Paris.
In 2019, she fronted the programme’s ground-breaking Wake Up To Menopause campaign and she took up endurance sport after competing in a BBC Breakfast Christmas cycling challenge.
She has gone onto compete internationally for the GB triathlon team in her age-group. Along with interviewing the UK's main political party leaders, career highlights on the show include talking to Sir David Attenborough, the Duchess of Cambridge, Billie Eilish, Jeff Goldblum, George Clooney, Angelina Jolie and Joanna Lumley.
BBC Breakfast Editor, Richard Frediani said: "Millions of viewers have regularly woken up with Louise for 20 years and welcomed her and BBC Breakfast into their homes. We will miss her brilliant journalism, good humour and boundless energy. She has been a tremendous BBC Breakfast colleague on and off-screen and will always be a friend to the team."
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