The 47-year-old, better known by his stage name MCA and who also supported Tibetan rights, died weeks after the pioneering white hip-hop act were inducted into the Rock and Roll Hall of Fame, although he was too ill to attend.
"It is with great sadness that we confirm that musician, rapper, activist and director Adam "MCA" Yauch .. passed away in his native New York City this morning after a near-three-year battle with cancer," said a statement.
The Beastie Boys sold over 40 million records and released four number one albums, including the first hip-hop album ever to top the Billboard 200, the band's 1986 debut full length, "Licensed To Ill."
They won three Grammys: two in 1998 -- best rap performance and best alternative music performance -- and one in 2007, best pop instrumental album, for "The Mix Up," according to the Grammys website.
The three-member band canceled a tour in 2009 after Yauch announced he had been diagnosed with cancer in a salivary gland. They have not appeared live since the summer of that year, said Rolling Stone.
Tributes began pouring in even before his death was confirmed -- on Twitter it became the top trending discussion topic, under the hashtag #RIPMCA.
"Another very sad day in Hip Hop. #MCARIP," said rapper Ice-T. adding: "I'm going Twitter silent today in honor of MCA.. Rest In Peace homie."
MC Hammer simply said: "R.I.P. Adam Yauch Beastie Boys," while British Culture Club star and DJ Boy George said: "Such sad news about Beastie Boy Adam Yauch. A fellow Buddhist and part of hip hop history!! R.I.P!"
Born in Brooklyn, Yauch taught himself to play bass in high school, forming a band for his 17th birthday party that would later become known the world over as Beastie Boys.
The rapper launched the band, initially a hard-core punk outfit, in 1979 with Mike "Mike D" Diamond and Adam "Ad-Rock" Horowitz, but they gradually moved towards hip hop, making it big with their 1986 album "Licensed to Ill."
Yauch was also involved in support for Tibet, and helped organize charity concerts for the cause in the 1990s. He recently became a vegan at the recommendation of his Tibetan doctors, TMZ reported.
He was also a founding member of film production and distribution company Oscilloscope Laboratories.
Yauch did not appear at a ceremony to induct the Beastie Boys into the Rock and Roll Hall of Fame in April, where Diamond and Horovitz read an acceptance speech on his behalf.
"I'd like to dedicate this to my brothers Adam and Mike," he wrote. "They walked the globe with me. It's also for anyone who has ever been touched by our band. This induction is as much ours as it is yours," it read.
His cancer treatment delayed the release of the group's most recent album, "Hot Sauce Committee, Pt. 2," which was already tipped to do well and could debut at the top of the Billboard chart after Yauch's death, CNN reported.
Tributes came not only from the hip hop community.
"Crushed to hear the news of Adam Yauch's passing. A true pioneer of art," said actor-singer Justin Timberlake, while actor Ben Stiller called him "a truly great musician & filmmaker."
British pop hearthrobs Duran Duran said: ""Rest in Peace Adam Yauch. Our condolences to your friends and family," while indie star Moby added: "I'm very very sad to hear of Adam Yauch's passing.
"He was a wonderful, generous, remarkable, and inspiring man and friend."
Yauch is survived by his wife Dechen and his daughter Tenzin Losel, as well as his parents Frances and Noel Yauch.
