Hill, who was previously editor of the Daily Star for five years, will be replaced by deputy editor Hugh Whittow
Whittow has been deputy editor at the Express since 2003, and was previously Hill's deputy at the Star, where he oversaw the launch of the Daily Star Sunday in 2002 - the UK's first new Sunday tabloid in 16 years.
Hill said in a statement last night: "It has been a huge privilege to edit two great national newspapers and now it's time to explore new directions. I want to thank my colleagues for their unstinting support and enthusiasm."
Publisher Richard Desmond added: "Peter has been a tremendous asset to the company. We all wish him and his family well for the future."
The Daily Express reported an average daily circulation of 623,689 in December, according to ABC - down 7.98 per cent year on year.
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