The pair will present the first hour of the morning magazine show at 6am later this year, before main hosts Lorraine Kelly and Aled Jones take over.
Ranvir Singh is currently on maternity leave, and has presented and reported on BBC North West Tonight since 2005.
Barbet currently presents 5 News for Channel 5, but has previously worked for BBC London while also covering for Bill Turnbull on Daybreak's rival show BBC Breakfast on occasions.
Singh said of her appointment: "I'm very excited about joining Lorraine, Aled and Matt. We'll be buzzing with all the morning news and having a laugh along the way I hope. I can't wait to get started!"
Barbet added: "I'm hugely excited to be joining the team at ITV. During my career to date I've been privileged to cover some massive stories, from the Afghan war to the royal wedding, and I'm looking forward to bringing that experience to my new role on Daybreak."
Daybreak editor David Kermode said: "We are so excited Matt and Ranvir are joining the team. They have the perfect blend of personality, authority and live broadcasting experience to make great breakfast TV. We can't wait to welcome them to the ITV family, to join Lorraine and Aled and the rest of the team".
Kelly and Jones were signed up as the new main hosts of Daybreak last month.
Matt Barbet was previously tipped for the main Daybreak presenter role back in November.