Fr Gerry Reynolds, a Redemptorist priest based at Clonard Monastery in west Belfast, died in the city's Royal Victoria Hospital on Monday morning aged 80.
He was well known for his cross-community work and efforts to tackle sectarianism.
The clergyman was originally from Co Limerick but worked at Clonard for more than 30 years, arriving when the Troubles were still raging.
Clonard was the focus of secret negotiations between Sinn Fein president Gerry Adams and SDLP leader John Hume that provided an impetus for the start of the peace process in the early 1990s.
The discussions were initiated by the late Fr Alec Reid, a close friend of Fr Reynolds.
Rector of Clonard Monastery, Fr Noel Kehoe, led the tributes.
"Fr Gerry past away in the care of the Royal Victoria hospital at 6.50am this morning, 30th November 2015 after a short illness," he said.
"He will be greatly missed by his Redemptorist confreres and colleagues, his family, friends, and the many people whose lives he touched through his Ecumenical, Peace and Reconciliation Ministries."
Mr Adams hailed the priest as a "champion of the peace process".
"Along with Fr Reid and Fr Des Wilson he was central to efforts to develop a peace process years before it eventually took root and he believed totally in the primacy of dialogue," he said.
"Fr Reynolds was part of the Clonard Church Ministry, a special peace-making ministry within the Redemptorist Order."
The Sinn Fein TD added: "Fr Reynolds embraced the importance of dialogue with other churches. He was a leader in ecumenical outreach and was instrumental in helping to facilitate discussions between members of the Protestant churches and Irish republicans.
"I want to extend to his family, and to colleagues in the Redemptorist Order, and to his many friends my sincerest condolences."
SDLP Assembly member Alex Attwood said he had lost a great friend: "Gerry Reynolds was a holy man who touched the lives of countless numbers."
He added: "He brought people together. Across our community, our churches and our conflict he worked quietly and relentlessly forging new relationships so that old differences could be resolved.
"He was forever working to make peace. His special work with Fr Alec Reid was one example of this. His life was defined by such work, seeking out the opportunity for good to prevail.
"He was devoted to the monastery, the people of Clonard and all of West Belfast. He brought Christian witness into private lives and public spaces.
"My family have also lost a great friend. Gerry was at our wedding, baptised our daughter Nora and concelebrated my mother's funeral mass in May.
"At birth, during life and at death Fr Gerry Reynolds was part of the lives of many, many people. He was deeply loved."
