With a career spanning decades, Seeger was credited with popularizing the hymn of the civil rights movement, "We Shall Overcome" and was known for renditions of songs like "If I had a Hammer" and "Where Have all the Flowers Gone."
He passed away of natural causes Monday at New York-Presbyterian Hospital where he was admitted a week earlier, his grandson, Kitama Cahill Jackson said, according to the New York Times.
Seeger played 12-string guitar or five-string banjo. He sang topical songs and children’s tunes as well as anthems, and often urged his audience to sing along.
He was an ardent social activist and his career mirrored the concerns of the American left, the Times said.
He sang for the labor movement in the 1940s and 1950s, for civil rights marches and anti-Vietnam War rallies in the 1960s.
He also intoned for environmental and antiwar causes in the 1970s and beyond.
He was a mentor to folk and topical singers in the '50s and '60s, among them Bob Dylan and Don McLean.
Bruce Springsteen drew on Seeger's work in his 2006 album, "We Shall Overcome: The Seeger Sessions," from Seeger’s repertoire of traditional music about turbulent American life.
At a Madison Square Garden concert celebrating Seeger’s 90th birthday, Springsteen introduced him as "a living archive of America’s music and conscience, a testament of the power of song and culture to nudge history along," The Times said.
"At some point, Pete Seeger decided he'd be a walking, singing reminder of all of America's history," The Boss said at that event.
"He'd be a living archive of America's music and conscience, a testament to the power of song and culture to nudge history along, to push American events towards a more humane and justified ends," said Springsteen.
Springsteen performed Woody Guthrie's "This Land Is Your Land" with Seeger at the Lincoln Memorial concert marking President Barack Obama's 2008 inauguration.
'No such thing as a wrong note'
Seeger had a gift for for inspiring people to sing along with him.
"There's no such thing as a wrong note as long as you're singing it," he told the 15,000-strong crowd at the 90th birthday celebration in New York.
Seeger inspired a generation of folk singers and musicians that included the Kingston Trio and Joan Baez. She once said: "We all owe our careers to Pete Seeger," the Los Angeles Times reported.
"Pete is America's tuning fork," author and oral historian Studs Terkel once said of him. "His songs capture the essence and beauty of this country."
He was born May 3, 1919, in Patterson, New York, into a musical family, the LA Times said.
His father, Charles Louis Seeger, was a noted musicologist and educator, and his mother, Constance de Clyver Edson, was a violinist and teacher.
Seeger was awarded the National Medal of Arts in 1994. That same year he was honored by the Kennedy Center.
In 1996, he was inducted into the Rock and Roll Hall of Fame, and won a Grammy Award for best traditional folk album for "Pete."
A 2008 album, "Pete Seeger at 89," also won a Grammy.
All told, he recorded dozens of albums and records, and compiled a series of instructional songbooks.
His wife, Toshi, whom he married in 1943, died in 2013. His survivors include son Danny and daughters Mika and Tinya Seeger-Jackson.