McCall is currently chief executive of Guardian Newspapers Limited and prior to that was managing director, a post she was appointed to in 2000, formally lining her up to succeed then GNL chief executive Caroline Marland.
She had risen up through the ranks at The Guardian, holding the posts of ad sales director and commercial director before being named deputy managing director in 1998.
GMG announced in January that Phillis, who has been chief executive for eight years, would be standing down in July following the news that he had been diagnosed with the early stages of bone marrow cancer, which would require a transplant later in the year.
Paul Myners, chairman of GMG, said: "Carolyn has a brilliant track record in running our national newspapers, and has a very clear and compelling vision for the future growth and strategy of the group."
McCall said: "GMG is well placed to take advantage of all the digital and other opportunities that are being created by the enormous changes in the media market."
She will take up her new role on August 1. Phillis will remain a member of the GMG board as a non-executive director while he receives treatment for his condition.
Last week, GMG announced would float a stake in its Auto Trader publisher Trader Media Group, which could raise as much as 拢400m.
Carolyn McCall CV
1982 Teacher at Holland Park School
1984 Risk analyst at Costain Group
1986 Joins The Guardian as a planner
1992 Display ad manager
1994 Deputy ad director
1995 Advertisement director
1997 Commercial director Guardian Newspapers Limited
1998 Deputy managing director GNL
April 2000 Managing director (designate) GNL
November 2000 Chief executive GNL
May 2006 Chief executive Guardian Media Group
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