Elle acting editor Jenny Dickinson is leaving the magazine to take up the same role at Harper's Bazaar.
She takes over in April from current acting editor Lucy Yeomans, who is leaving the magazine to take up a new role with the Net-A-Porter Group.
The magazine's previous editor was Fiona MacPherson.
Dickinson has been acting editor at Elle – also owned by Hearst Magazines UK - for the past year while editor-in-chief Lorraine Candy was on maternity leave.
She joined Elle in 2008 and was previously the magazine's deputy editor, beauty director and associate editor. Before that she was deputy production editor at New Woman and production editor at women's weekly title First.
Arnaud de Puyfontaine, chief executive of Hearst Magazines UK, said: 'I am delighted that Jenny has agreed to edit Harper's Bazaar. Not only does she have a fantastic knowledge of the fashion industry, but is also a highly respected journalist and editor.
'Jenny has done a superb job editing ELLE Magazine in Lorraine's absence and it is timely that we can transfer her skills and talent from one of our iconic brands to another."
He added: 'Lucy has been Editor of Harper's Bazaar for the past twelve years and during her tenure the brand has gone from strength to strength.
'Under Lucy's editorship, Harper's Bazaar has won the PPA Magazine of the Year award and the BSME Editors Editor of the Year Award.
'Lucy is highly respected by the world's finest fashion designers, writers, artists and photographers – many of whom have featured in the pages of Bazaar or collaborated with the magazine to create ground-breaking covers and editorial content.
'We wish Lucy happiness in this next phase of her life and look forward to working with Jenny to build on the success of this iconic brand in the coming months".