Reid's move from the BBC Breakfast sofa, where she has been hugely popular with audiences, follows days of speculation about the move.
ITV announced that the Strictly Come Dancing finalist would be joined by former GMTV star Ben Shephard, Charlotte Hawkins and Sean Fletcher on the new show.
They will join the channel as ITV's main weekday presenters, between 6am and 8.30am, on the newly-named breakfast show Good Morning Britain.
The announcement comes after Reid's agent confirmed that the mother of three - who was absent from BBC Breakfast this morning - had split from her long-term partner Dominic Cotton.
ITV director of daytime Helen Warner said: "I'm delighted to welcome all four presenters to the ITV Breakfast family.
"ITV has a first-class roster of breakfast and daytime talent, both on and off screen, and I'm thrilled to be expanding this.
"Our overriding aim is to continue to improve our breakfast programming for our viewers, and we have been working for some time behind the scenes developing the next chapter of our offering."
She said the new show would have an emphasis on news.
"Engaging, news-driven content is our number one priority and will be at the heart of everything we do on Good Morning Britain. I believe we have a top team in place to deliver this and make this a compelling proposition to wake up to in the morning."
The announcement is the latest attempt by ITV to compete against BBC Breakfast since Daybreak launched, with much fanfare, in 2010.
Launch presenters Adrian Chiles and Christine Bleakley were dropped a little over a year after the programme, which replaced GMTV, first went on air.
It was later given an overhaul, with Aled Jones and Lorraine Kelly fronting the programme.
Jones will now present a new weekend morning show, Weekend, while Kelly will continue to front her own show, Lorraine, between 8.30am and 9.25am.
The latest revamp revives the name which was used by the station's morning show when it launched a breakfast TV service in 1983.
Hawkins is best known for Sky News show Sunrise, while Fletcher comes from Sky Sports.
Reid's profile on BBC Breakfast increased following the departure of Sian Williams when the show moved from London to Salford in 2012.
She was later named the most popular BBC breakfast host of all time.
While her outfits won her plenty of male admirers, the presenter has also raised eyebrows for occasionally "showing too much leg or cleavage".
But she hit back, saying that the focus on women in TV was a "fact of life" and added: "People seem to be shocked that women have breasts. There'll be complaints about the fact that there is literally a shadow showing."
She also dismissed the Twitter frenzy caused by her "flirty" interview with Arctic Monkeys frontman Alex Turner, calling it a "fuss about nothing".
The 43-year-old's profile increased further with Strictly, when she came second to Abbey Clancy.
Fellow competitor Fiona Fullerton claimed Reid had approached the BBC1 show "with a PR campaign driven with military precision".
Reid has previously dismissed reports of a move to ITV, saying: "If you cut me open I would bleed BBC. I said when BBC Breakfast moved to Salford that the BBC runs through me like a stick of rock - and nothing has changed."
The presenter was reportedly offered £1 million, said to be four times more than her current salary, to move to ITV.
Her big break came while she worked as a reporter on BBC News 24, when she filled in for a presenter who had failed to turn up.
The split in her personal life was confirmed after her ex-partner was spotted on a dating website, where he was listed as "separated" and looking for a woman aged 35 to 45.
With around one million viewers, Daybreak has lost out in the ratings battle to BBC Breakfast, which has pulled in around 500,000 more.
Reid has been commuting from London to Salford, and called the long journey "liberating", adding: "It genuinely works for me."