The Sun on Sunday will publish for the first time next weekend, News International has announced.
An internal memo sent to all staff at Rupert's Murdoch's company said the media mogul will be in London for the launch.
The email said: "Rupert Murdoch said during his visit on Friday that a new Sunday title would be published 'very soon' - and that is a week from today.
"Rupert will be staying in London to oversee the launch."
Speculation about a Sunday edition of the biggest selling UK daily newspaper has been mounting since the closure of the News Of The World (NOTW) after the hacking scandal.
The email from Tom Mockridge, News International's chief executive, acknowledged the parent company's previous wrongdoing and said it was "fundamentally changing".
It read: "As you know, News Corporation has made clear its determination to sort out what has gone wrong in the past and we are fundamentally changing how we operate as a business.
"The commitment of News Corporation to invest in a new edition is the strongest possible message of support we could wish for."
He told staff they would have to act quickly over the coming days.
"This is our moment," he wrote.
"I am sure every one of us will seize the opportunity to pull together and deliver a great new dawn for The Sun this Sunday."
Sources have told Sky News The Sun's editor Dominic Mohan will also edit the Sun on Sunday.
The source said: "There will be some sharing of staff. [It] will be a seventh day publication rather than a new title."
David Wooding, former political editor of the NOTW, told Sky News: "It caught me by surprise.
"Mr Murdoch came round the editorial floor on Friday and said he was launching it very soon.
"We heard rumours of a date in April. This evening, astonishingly, we are told it's going to happen next week."
He added: "We don't even know what the staffing levels will be at this stage.
"I'm told there will be extra staff taken on but this is not the News Of The World in another guise, this is The Sun publishing on another day."
Mr Murdoch flew into the UK on Thursday to take personal control over the latest scandal to hit one of his titles.
The following day he moved to quell growing disquiet at The Sun by lifting the suspensions of all arrested staff.
While pledging "unwavering support" for his journalists, he also vowed to root out wrongdoing at News International.
The tabloid has been rocked by the arrests of 10 current and former senior reporters and executives since November over alleged corrupt payments to public officials.
Campaigners from Hacked Off, which called for an inquiry into phone hacking, said: "The victims of phone hacking and questionable practices do not oppose the offering of the choice of another Sunday title in the newspaper market - they only care that it is produced from ethical and legal news-gathering techniques and that the existing code of practice is observed.
"This new paper is an opportunity for News International to show that it has turned over a new leaf and will behave legally and professionally. Part of that would be an acknowledgement by all its staff that wholesale bribery of public officials for tip-offs and private information is no part of ethical journalism."
Some Sun journalists have voiced anger that News Corporation's Management Standards Committee (MSC) - formed to clean up the company following the phone-hacking scandal - gave police the information that led to the arrests.