The Independent and Independent on Sunday newspapers have been sold to Russian billionaire Alexander Lebedev, owner of the London Evening Standard.
The oligarch bought the loss-making paper from Irish company Independent News & Media (INM) for £1, the cost of one daily edition of the newspaper.
As part of the deal, INM agreed to pay Mr Lebedev's Independent Print Limited (IPL) £9.25m over the next 10 months.
A deal between the two parties has been under discussion for many months.
The payment from INM to the new owners is to cover "all future trading liabilities and obligations".
IPL said the agreement "provides a commitment by the Lebedev family to invest in the newspapers, which are currently loss-making, and inject new energy and impetus into them".
Speaking to the AFP news agency in Moscow shortly before the deal was announced, Mr Lebedev said, "I do not treat newspapers as business. I treat them as my responsibility."
"I think newspapers are the only instrument which, through investigative reporting, can ferret out everything about international corruption," he added.
INM chief executive Gavin O'Reilly said the deal "is the most satisfactory and positive outcome for the titles, their staff and for INM's shareholders."
The sale still needs to be approved by the Irish competition authorities.
As a result of the sale, which is expected to be completed in May, INM UK head Ivan Fallon has retired from the group.
Both titles have, historically, struggled to get enough readers to generate sufficient profits, and this has been exacerbated in recent years by competition from free, online news.
They have also suffered during the downturn as advertising revenue has fallen sharply.
Mr Lebedev, a former KGB agent, bought the Evening Standard, also for £1, last year.
The paper is now given away free, and has seen its readership grow sharply as a result.
There is speculation that Mr Lebedev also plans to give away copies of the Independent titles.
The National Union of Journalists said it had "no concerns about [Mr Lebedev's] editorial influence.
"We would like to think Mr Lebedev has an imaginative plan with good editorial investment in journalism, and a good distribution plan to maintain and increase the circulation of the paper.
"We would also like to see all the speculation about editorship resolved quickly."