Muscat, 48, is Fairfax's tenth CEO in as many years.
Muscat, who takes over on August 1, replaces Bob Mansfield who resigned in mid-April following disputes with Black and key directors about the speed of reforms at the company which publishes the Sydney Morning Herald, The Age in Melbourne, the Financial Review and a stable of regional and Sunday newspapers and national magazines.
Muscat will have to deal with management instability as well as tensions among Fairfax's three major shareholders--Black's The Telegraph plc with 25%, and prospective raiders, Kerry Packer with 17% and Mr. Murdoch with 5%.
He joined News Limited 27 years ago and rapidly moved through the ranks, becoming heir apparent to News Limited's CEO Ken Cowley. His aspirations were dealt a blow last year when Murdoch's elder son Lachlan, 24, was appointed deputy-CEO.