NEWS International chief executive Tom Mockridge is to quit the job at the end of the month.
He is said to be stepping down to “pursue outside opportunities”.
”Whether it was his early days with our newspaper group in Australia, his incredible work building Sky Italia, or his steadfast leadership of News International, Tom has always been a skilled executive and a trusted friend.
“His decision to step down is absolutely and entirely his own. I am sorry to see him leave us but I know he will be a great success wherever he goes.”
Mockridge, a former newspaper journalist, joined News Ltd in Australia in 1991, where he worked with Murdoch’s son James at Star TV.
He later moved back to his native New Zealand to oversee the company's media operations there.
After launching Sky Italia he became chief executive of European Television and served on the boards of BSkyB and Sky Deutschland, and is chair of Fox Turkey.
Last week Mockridge backed calls for a “tough” new press watchdog but warned that state-backed regulation would put too much power in the hands of politicians.
He said: “As a company we are keen to play our full part, with others in our industry, in creating a new body that commands the confidence of the public.
”We believe that this can be achieved without statutory regulation - and welcome the Prime Minister's rejection of that proposal.
“We accept that a new system should be independent, have a standards code, a means of resolving disputes, the power to demand prominent apologies and the ability to levy heavy fines.”
He also insisted phone hacking victims like Milly Dowler's parents should not be able to determine how the press is regulated in the future, in an interview with BBC Radio 4.
He added: “They (victims) have a unique moral voice in this but it doesn't mean they determine the legislation of the state that governs free speech.”
Mockridge said he was “genuinely shocked” about the allegations of phone hacking at the company.
But he insisted The Sun would not be shut down like its now defunct Sunday sister paper, The News of the World, if more allegations emerged.