Simon and Garfunkel will reunite for a tour 33 years after they split up.
"What we had was a friendship that was estranged," said Paul Simon, right
The pair, who were among the most popular and influential artists of the 60s, will play in the US this autumn.
Paul Simon and Art Garfunkel went their separate ways after their 1970 album Bridge Over Troubled Water, but have performed together occasionally since.
Their most recent appearance was at the Grammy Awards in February, where they sang The Sound of Silence.
They made the announcement at a New York nightclub on Tuesday with a performance of their 1970 hit The Boxer.
"Because we tend to [go on tour] every 10 to 12 years, I think this is probably going to be the last time that we're going to do this," Simon said.
"I never actually thought that we'd lost our ability to
sing together and have a blend," he added.
"What we had was a friendship that was estranged, and the Grammys was an opportunity to put that behind us."
Garfunkel said it was "truly a joy" to sing again with Simon, whom he has known for 50 years.
"It's family, the two of us," he said. "Our moms know each other. They're still alive. There has been a deep, buried affection for the last decade or so and it was the Grammys that forced it out of burial."
Garfunkel's website said the Old Friends tour would start on 18 October in Michigan and visit 30 cities, ending in mid-December.
Simon and Garfunkel have won four Grammy Awards as a duo
Tickets will go on sale on Monday, the site said.
After meeting as children, the pair's first single as Simon and Garfunkel, A Hazy Shade Of Winter, was released in 1966.
That was followed by songs like Mrs Robinson, Scarborough Fair and The Boxer, which were hits around the world.
Despite often acrimonious relations after they split, they released a new single, My Little Town, together in 1975 and played to 500,000 people in New York's Central Park in 1981.
A US arena tour took place two years later and the duo played 21 sell-out dates in New York in 1993.
"We've known each other since the age of 11. Forgive, forget, move on. It's not like you live forever in life," Simon said at Tuesday's press conference.
A new greatest hits album with 32 tracks will be released to coincide with the tour.