"The family of Robin Gibb, of the Bee Gees, announce with great sadness that Robin passed away today following his long battle with cancer and intestinal surgery," his rep said in a statement.
"The family have asked that their privacy is respected at this very difficult time."
Along with his twin Maurice and brother Barry, Gibb formed the Bee Gees (in part, to stand for the Brothers Gibb), and together they recorded decades of hit songs, including the iconic Stayin' Alive.
In October 2011, the Songwriting Hall of Famer fell ill with intestinal problems and was taken from his home near Thame, England, to the John Radcliffe Hospital in Oxford for tests and treatment for inflammation of the colon, his rep said.
His wife Dwina – with whom he had a son, Robin-John – said at the time that she was "desperately worried" about his health, given the Gibb family history of gastrointestinal problems. Robin's twin Maurice died of intestinal complications in 2003.
Gibb left the hospital four days later. In mid-April 2012, he was in a coma, the result of pneumonia, and yet rallied and regained consciousness more than a week later.
Despite being best known for the songs like Stayin' Alive that helped make the 1977 John Travolta movie Saturday Night Fever such an enduring hit (and its soundtrack a 15-time platinum seller), Gibb and his brothers' career had started a decade earlier.
Then, rather than Barry's falsetto vocals, it was Robin's pitch-changing vibrato that was the early lead voice in the group.
The Australian BeatlesIn fact, after their first taste of success in the late 1960s – when they were nicknamed the Australian Beatles because the family had emigrated Down Under from England – Gibb broke away from his brothers to embark on a solo career. His single Saved By The Bell went on to sell a million copies in the U.K.
In 1968, he married Molly Hullis, a secretary who worked for his manager, Robert Stigwood. They had two children before divorcing in 1980 after years of living separately.
Despite their success, the family was not without its share of tragedy. In 1988, the Gibbs' younger brother Andy died of inflammation of the heart. He was only 30. Today, only Barry is left of the famous singing clan.
Up until his death, Robin was still involved in music, and in the summer of 2011 worked on a classical concept album, The Requiem For Titanic, composing it alongside his son Robin-John – although he was too ill with pneumonia to attend its London premiere, April 10, 2012.
He also had taken a prominent role in safeguarding the rights of composers when he became President of CISAC, the International Confederation of Authors and Composers Societies.
Gibb also had hinted that there was more to come from the two brothers, telling Music Week that he had big plans for 2012: "When you have got one of the most successful catalogues in the world today, with Barry, you get excited, but get to cherry pick!"