Cullen said he had made the decision after a year of balancing the breakfast radio role and television commitments.
Several former Nine employees have said the handling 'reeks of double standards'.
From Monday 22 September, Seven will roll out Winning Arvo - a new afternoon line-up blending hit game shows with live news...
The veteran presenter revealed the move on Gold 104.3’s Christian O’Connell Show and will continue his radio role alongside the TV comeback.
Plus: Greg Wallace, Danielle Veivers, Warwick Kiel, and Matt Holmes.
See the top industry stories trending today.
Adrian Portelli: 'My company has always been about changing the lives of everyday Australians'.
Ray Kuka: 'He's one of the nicest guys in television.'
Plus: Tina Provis, Mel Duffy, Alex Cullen and Amanda Unwin.
Alex Cullen will join the show, filling a gap left by the recently departed co-host Jack Post, who announced his shock departure...
Plus: Kurt Burnette, Seb Costello, Orange Line, Brendan Fevloa steps back from radio.
'Thanks for having me'.
Danika Mason: 'This is a full-circle moment for me'.