Meanwhile, News UK head of comms Helen Collier has been promoted to deputy director of comms.
Dunlop previously worked at News UK as head of external comms before moving to New York in 2013 to become VP, strategy and planning, ahead of the company split when the publishing division separated from the TV and film arm. She joined News Corp in 2001, initially working for News Corp Europe.
Rebekah Brooks, CEO of News UK, said: "Daisy has an unrivalled knowledge of this company and our industry and I am delighted that she will be joining us in London. As a skilled communicator she will be telling our story to key stakeholders and clients, as well as managing our internal communications and CSR strategies."
Dunlop, who starts her new role in mid-February, said: "News UK is a true investor in professional journalism and its audiences are loyal and valuable to advertisers. I look forward to ensuring that this story gets the visibility it deserves."
In November, Harri announced that he was to leave his position at The Sun and The Times publisher at the end of 2015 after three-and-a-half years, saying it was "job done". He later joined Virgin Media owner Liberty Global in the new role of managing director, external comms.