Malcolm Denmark, director of Iconic Newspapers Ltd, is understood to have paid €8.5m to Johnston Press in the deal.
Johnston Press paid about €250m for the titles nine years ago.
Mr Denmark said: “We are delighted to be here in Ireland. We know that we are just custodians now of some very important brands in Ireland.
“We want to invest in those brands and make sure that the communities that they serve are very involved in their future and their progress.”
The titles include the Limerick Leader, the Leinster Leader, the Kilkenny People, and the Donegal Democrat.
When asked how much he paid for the titles, Mr Denmark refused to dismiss reports of €8.5m. “That is not being denied,” he said.
He also assured those employed at the various titles that all jobs are secure, insisting “we are here to invest in the market”.
“It is a private business; we are not a corporate, not a listed company. The vehicle I have formed in Ireland to buy these newspapers is Iconic newspapers.”
Though based in London, Mr Denmark, 58, who set up the company last November, insisted he is looking forward to becoming more of an Irishman and to spending more time here.
“This is a first venture into local papers but my whole business and my whole career, my whole background, has been newspapers,” he said.
“I have a long history or working with newspapers either as a supplier or a customer,” said the father of two.
Editor of the Limerick Leader, Alan English, said the newspaper now in its 125h year is moving into a new phase.
“It’s a new dawn and I’m very much looking forward to working with Malcolm and the new team.”