Many celebrities took to Twitter to share their thoughts on the beloved musician.
Playing music "kept him going during the toughest of times". The brothers formed the Allman Joys, a prelude to formation of the Allman Brothers band once they left for Los Angeles and started studio sessions and recording.
The group, which originally featured Allman's older brother, Duane, on lead and slide guitar, was also a precursor to a generation of popular jam bands, like Widespread Panic and Phish, whose music features labyrinthine instrumental exchanges.
Born in Nashville, Tennessee, the rock star known for his long blond hair was raised in Florida by a single mother after his father was shot to death.
The Allman Brothers Band's star was 69.
"I. proceeded to wear that son of a b***h out", Allman later told Rolling Stone.
More concise originals like "Midnight Rider" and "Melissa", as well as Allman's renditions of blues classics like "Statesboro Blues" and "Done Somebody Wrong", revealed his singular affinity with the black Southern musical vernacular.
The band was honoured with a lifetime achievement Grammy in 2012. He had battled health problems for many years, and had undergone a liver transplant in 2010 after a diagnosis of hepatitis C. He would go on to a solo career, as well as taking part in reformations of the Allman Brothers before bringing down the curtain on the group in 2014 with a four-hour show in NY that included original members Butch Trucks and Jai Johanny Johanson. But he was killed in a motorcycle accident in October 1971, just months after recording the Fillmore shows.
Allman stayed at it for more than 50 years.
Their 1973 album Brothers and Sisters became their biggest hit, and Allman pursued a solo career afterward, releasing his debut album, Laid Back the same year. He is survived by his wife Shannon and his children, Devon, Elijah Blue, Delilah Island Kurtom, and Layla Brooklyn Allman as well as three grandchildren and a large extended family.
In a profession that sees superlatives thrown around carelessly, Allman truly was one of a kind; a legend. They had just finished Capricorn Studios in Macon, Georgia - and that was a great studio with all of 12 tracks - and I said we've got a perfectly good studio here.
"The Allmans were clearly the architects for an entire genre of music-even if they could play circles around the other Southern Rock bands, they created a template that others followed and that you still hear on the radio every day", Light says.