Transport chair Arnold has quit the ABC and is moving to CBS News.
Arnold said the ABC News job was a dream come true and he had been told he could make a lot of money at CBS News by “working like a hero”.
But it’s been “tough and frustrating” to work there, he said.
He said he had a “lack of confidence” in the ABC’s editorial team and said the staff needed “a fresh start” after the departure of former chief executive James Pritchard.
“It is the only outlet that I have ever worked for in the history of ABC news,” he said in a statement.
“I have a lot to offer the organisation and I am grateful to everyone who has supported me in my career.”
Pritchard was sacked last week after nearly six years at the helm.ABC News was axed by Pritchett’s successor, Anthony Albanese, and the corporation announced it was reopening on Tuesday.