News International chief steps down
Mockridge, who took over the position in July 2011, is stepping down to "pursue outside opportunities".
Rupert Murdoch, chairman and chief executive of News Corporation, said: "For nearly 22 years, it has been my pleasure to have Tom Mockridge as a colleague.
"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.
Mockridge took over leadership of News International, the publishing arm of News Corporation which owns the Times, the Sunday Times, The Sun and The Sun Sunday, from Rebekah Brooks at the height of the phone hacking scandal.
The former newspaper journalist joined News Ltd in Australia in 1991, where he worked with James Murdoch, deputy chief operating officer of News Corporation, at Star TV, before moving to his native country of New Zealand, where he oversaw the company's newspaper and TV operations.
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."
© 2012 Press Association