The current presenter will become entertainment editor while Christine Bleakley and Adrian Chiles will front the show.
'This is a fantastic opportunity to spread my wings in an exciting new role,' says Kate, 43.
'Showbusiness is big business and Daybreak will be the place for all the big interviews and stories. Movies, TV and music are of massive interest to our viewers.'
Kate could still host Daybreak when Christine, 31, is away.
But LA correspondent Carla Romano and TV expert Richard Arnold will not be involved in the new show.
'The last 10 years at GMTV have been like a rollercoaster... exciting, scary, hilarious and unpredictable,' Carla, 41, tells the Daily Mirror.
'But never dull. Here in LA, I have interviewed and got to know some of the world's biggest stars.'
Richard, 40, adds: 'I look forward to the exciting projects ahead.'
Daybreak will launch in September.