Alison Phillips, the editor-in-chief for The Mirror newspaper, is to step down from her role at the end of January.
She said she was proud to be part of a team which showed that “great journalism can be done with kindness”.
Phillips will be replaced on an interim basis by Caroline Waterston, editor-in-chief of Reach plc’s national magazines and supplements.
Reach plc owns publications including The Mirror and Manchester Evening News.
Its chief executive Jim Mullen praised Phillips’ “dedication”.
Reach, which employs about 4,500 people, said in July that the cost of printing newspapers had risen by 60% due to high energy.
During Phillips’ tenure, the newspaper reports broke about the row over Dominic Cummings controversially travelling in 2020 to Barnard Castle during lockdown in the Covid pandemic, and claiming he had been trying to test his vision.
Phillips’ departure comes amid wider challenges for the Mirror and Reach.