This marks the first time that the former Sky Italia chief executive has publicly discussed press standards since he was parachuted into the UK newspaper publisher following the resignation of Rebekah Brooks.
New Zealand-born Mockridge was previously a journalist under Rupert Murdoch's media empire in Australia, but moved to Italy in 2002 to play a key role in the broadcasting merger that created the Sky Italia pay-TV business.
Lord Leveson's inquiry is expected to quiz him on the changes at News International since the shock closure of the News of the World in July.
Also appearing at the inquiry next week will be a string of high-profile newspaper executives, including The Guardian's editor-in-chief Alan Rusbridger and Chris Elliott, the readers' editor at the paper.
News International will be represented by Rupert Pennant-Rea, the former deputy governor of the Bank of England and independent board member of Times Newspaper Holdings, which publishes The Times and Sunday Times.
James Harding, the editor of The Times, will also give evidence, along with his Sunday Times counterpart John Witherow.
Richard Wallace, Tina Weaver and Lloyd Embley, the editors of the Daily Mirror, Sunday Mirror and People respectively, are all scheduled to appear at the high court inquiry.
Trinity Mirror chief executive Sly Bailey is to give evidence, as well as Sunday Mirror TV critic Kevin O'Sullivan.
The Wednesday session will be devoted to the celebrity magazines, including testimony from Rosie Nixon, Lisa Byrne and Lucie Cave, the editors of Hello!, OK! and Heat respectively.
In the afternoon of that day, Lord Leveson will quiz the regional papers, including the editors of the Yorkshire Post, Belfast Telegraph, Manchester Evening News, and Scotsman, among others.
Yesterday at the inquiry, the Daily Express and Daily Star owner Richard Desmond rejected criticism of his newspapers over their coverage of the disappearance of Madeleine McCann.
Desmond, the first newspaper proprietor to give evidence, claimed the Express had been made a "scapegoat" over what other newspapers were also doing.
More Leveson coverage:
> Daily Mail receives 400 Pippa Middleton pictures a day
> Hugh Grant suspects Mail on Sunday phone hacking
> The Daily Telegraph paid source £150k for MPs' expenses story
> Charlotte Church offered coverage deal to sing at Murdoch wedding