Tributes have been paid to Mr Fitzpatrick, who owned the paper since the early 1980s.
According to the newspaper, his life came to an end this morning.
The Irish News, of which Mr Fizpatrick was chairman, is one of three daily titles in Northern Ireland, alongside the News Letter and Belfast Telegraph.
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The Taoiseach Micheál Martin said: “I had the great privilege of knowing and interacting with Jim over many years. He was, in every respect, a true gentleman.”
Mr Martin added: “In his decades-long stewardship of the Irish News, he was a profoundly important advocate for an end to violence in the north. His role in the earliest days of the embryonic peace process is not widely known, but it was crucial.”
Mr Fitzpatrick was married to the late Alice Fitzpatrick, and they had eight children, Anne, Brid, Bernard, Eileen, Dominic, Clare, Jim [the BBC presenter], and Andrew.
Another of those children is managing director of the Irish News, Dominic Fitzpatrick.
He said on behalf of the Fitzpatricks: “As a family we were blessed with incredible parents.
“Dad was an inspiration to so many people. His desire to be involved in the Irish News was driven by a belief that society needed a newspaper that could stand for truth and justice, particularly at such a turbulent time in history.
“Under his direction the paper has been transformed into the success it is today.”
He said his father also helped “in the search for peace in Ireland, working quietly but effectively in the background”.
The editor of the Irish News Noel Doran said Mr Fitzpatrick was a “giant of the newspaper industry as well as a key figure in the search for peace and reconciliation in Ireland who also had significant roles in law, business and the arts”.
He added: “Although he maintained a low profile, he was a noted philanthropist who probably had the strongest personal faith of anyone I have ever met.”
Ben Lowry, the editor of the News Letter, said: “Jim Fitzpatrick was indeed a giant of the Northern Ireland newspaper industry.
“I remember for example the way in which he stood with his editor Noel Doran as they very publicly threw the full weight of the Irish News behind an appeal against a libel case that they lost over a bad restaurant review that the newspaper ran.
“It was important that such a ridiculous verdict in Northern Ireland, which would never have happened in London, was overturned, and Mr Fitzpatrick gave crucial weight to that legal challenge in defence of free speech.
“He was also a key voice in promoting peaceful, democratic solutions to the Troubles.
“Jim Fitzpatrick will be sorely missed, in the newspaper world and beyond.”
The leader of the SDLP, Colum Eastwood MP, said: “Jim Fitzpatrick was one of the giants of news in Ireland. During the most difficult periods of our recent past, Jim was fearlessly devoted to telling the stories of ordinary people who had suffered the most extraordinary loss and he did it without favour, even when it meant putting himself at odds with the men of violence. He was a man committed to the truth, to fairness and to peace on our island.
“His strong stewardship of the Irish News and his absolute belief in the primacy of democracy and the principles of non-violence contributed in an inestimable way to the peace we enjoy today. He was one of the people who helped sustain the embers of a fledgling peace process and his contribution cannot be underestimated.”
The SDLP South Belfast MP Claire Hanna said: “Jim Fitzpatrick was a man of integrity, faith, courtesy, kindness, and approachability. His contribution to the life of our island, as a lawyer, businessman and through the Irish News, has been immense. A dedicated and unwavering democratic nationalist, he held firm against the use of violence in the promotion of any cause.
“Jim lived for and loved his family, especially his late wife Alice, and their children who he was so proud of. Our thoughts are with the Fitzpatrick family today.
“Ar dheis Dé go mbeidh a anam dílis agus I measc Naomh na hÉireann go mbeidh sé.”
Dominic Fitzpatrick also said of his father: “He had a morning prayer which he said every day and it pretty much summed up his attitude to life. He saw every day in life as an opportunity to be seized, a gift from God not to be wasted. A day where he would be thoughtful, generous and helpful to others and lived without regret.”
Micheál Martin said of Jim Fitzpatrick: “In his support for and leadership of the Chamber of Commerce in Belfast, he brought together people from all backgrounds in common constructive cause and was an example of true civic leadership.”
Funeral arrangements will be confirmed later.