Makem died Wednesday in Dover, New Hampshire, where he lived for many years.
The Irish-born Makem, who came to America in the 1950s to seek work as an actor, grew to international fame while performing with the band The Clancy Brothers and Tommy Makem. The brothers, also from Ireland, were Tom, Liam and Paddy Clancy.
Thursday, as fans and friends logged onto Makem's web site to express their sorrow, Irish President Mary McAleese sent condolences on behalf of her countrymen.
"In life, Tommy brought happiness and joy to hundreds of thousands of fans the world over," said McAleese. "Always the consummate musician, he was also a superb ambassador for the country, and one of whom we will always be proud."
Armed with his banjo, tin whistle, poetry, stagecraft and his baritone voice, Makem helped spread stories and songs of Irish culture around the world.
He brought audiences to tears with "Four Green Fields," an allegorical song about a woman whose sons died trying to prevent strangers from taking her fields. Other songs included "Gentle Annie" and "Red Is the Rose."
"He just had the knack of making an audience laugh or cry. ... holding them in his hands," Liam Clancy told RTE Radio in Dublin, Ireland.
The New York Times in 1967 called them "an eight-legged, ambulatory chamber of commerce for the green isle they love so well... At one point, Irish teenagers were paying as much homage to them as to the Beatles."
After touring for about nine years as The Clancy Brothers and Tommy Makem, he struck out on his own, but he remained friends with the brothers. Tom Clancy died in 1990 and Paddy in 1998.
Back in the 1950s, Makem and his friends viewed the success of their first few albums — "The Rising of the Moon" and a collection of drinking songs — as a fluke.
In a 1994 Associated Press interview, Makem recalled he was astonished when a Chicago club offered him more money to sing for a week than he was getting for acting with a repertory company.
"I was the opening act for Josh White. I felt sort of silly, coming out and singing unaccompanied, and then Josh coming out and almost making the guitar talk," he said.
As their fame spread, they appeared on "The Ed Sullivan Show" and other major TV shows, and headlined concerts at Carnegie Hall and London's Royal Albert Hall.
A young Bob Dylan was one of the folk singers who got to know Makem and the Clancys during the early 1960s.
"Topical songs weren't protest songs," Dylan wrote in his memoir "Chronicles Volume One." "What I was hearing pretty regularly, though, were rebellion songs, and those really moved me. The Clancy Brothers — Tom, Paddy and Liam — and their buddy Tommy Makem sang them all the time."
In 1992, Makem and the Clancys were among the stars at Madison Square Garden in New York, joining Eric Clapton, George Harrison, Johnny Cash, Willie Nelson, Stevie Wonder, Tracy Chapman and many others in a tribute to Dylan.
Makem loved his work and had a quick answer a few years ago when asked if he'd thought about retirement.
"Yes, of course," said Makem, who enjoyed being known as both the Godfather of Irish music and the modern day Bard of Armagh. "I retire every night. And in the morning when I awake, I realize just how lucky and privileged I am to be able to continue doing the things I love to do."
Even while battling cancer, he continued to perform. In April - with the Spain Brothers - he won Best Folk Act at the Spotlight Awards in Portsmouth, N.H., and in July, he picked up an honorary degree from the University of Ulster in Belfast and returned to Armagh.
"He had very much wanted to get over there," said his son, Conor Makem. "I think he knew it might have been his last time over."