Frazier had already been receiving get-well messages from fellow boxers and fans alike, following the diagnosis last month which saw him in and out of hospital.
His death was announced in a statement from his family, who added that details of "our father's homecoming celebration" would be made known as soon as possible.
Sinn Féin's Alex Maskey said he was deeply saddened by the loss and recalled how he invited the boxing legend to Belfast, after meeting him in Philadelphia in 2003.
"Just a couple of months later, Joe visited the city for a hectic couple of days of events," the former Lord Mayor of Belfast said.
"It was a fantastic treat for young boxers and old to get to meet a world boxing legend and he had time for everyone he met."
Joe thoroughly enjoyed his visit to Belfast and commented that the people treated him like a current world champion.
Alex Maskey, Sinn Féin
Mr Maskey added: "I have already been in touch with Joe's family to express mine and the city of Belfast's condolences on the passing of a true boxing legend - and one who has left us with many fond memories, especially of his visit here."
Gerry Storey, from Holy Family boxing club in north Belfast, remembers meeting Frazier on many occasions - both in Belfast and in the US.
"Fantastic the crowds that followed him - he was a terrific ambassador for Philadelphia," he said.
"Frazier would have been one of the all-time greats, up there with the best of them.
"He was a terrific fighter, a terrific puncher and a great heart."
Mr Storey added that the boxer understood the importance of what Holy Family was trying to achieve in bringing young people together during the Troubles in Northern Ireland.
"He knew from the hardships that he had coming up in South Carolina... he always believed in talking to keep things going," he said.
Hailed as one of the greatest boxers ever to grace the sport, Frazier made history with his bouts with none other than Muhammad Ali - including the unforgettable Fight of the Century and the Thrilla in Manila.
There was little love lost between the two for many years, in the ring or out of it.
We always said sport can change the world and he was a big believer in that.
Gerry Storey, Holy Family
As Ali lit the Olympic torch in Atlanta in 1996, Frazier was asked by one reporter what he thought - only to reply: "They should have thrown him in."
But he did mellow in recent years and, just before the 40th anniversary of his win over Ali earlier this year - Frazier said he no longer felt any bitterness toward his long-time nemesis.
"I forgive him," he said. "He's in a bad way."
In a statement, Ali said: "I will always remember Joe with respect and admiration. My sympathy goes out to his family and loved ones."
Don King, who promoted the Thrilla in Manila - later branded by Ali as the "closest thing to dying" he knew - was described by a spokesman as too upset to talk about Frazier's death.
Bob Arum, who once promoted Ali, spoke of his sadness and said Frazier was "inspirational".
He added: "I'm torn up by Joe dying at this relatively young age. I can't say enough about Joe - Joe Frazier should be remembered as one of the greatest fighters of all time."
World welterweight champion Manny Pacquiao - who learned of Frazier's death shortly after he arrived in Las Vegas for his fight this Saturday with Juan Manuel Marquez - added: "Boxing lost a great champion, and the sport lost a great ambassador.
"My prayers go out to his family."
Check out pictures from throughout Joe Frazier's legendary career - including those epic fights with Ali - in our gallery Smokin' Joe Frazier!