The musician, who was known for writing one of the band's biggest hits, Ramblin' Man, died on Thursday "surrounded by his family" at his home in Osprey, Florida.
A statement posted to Betts' social media said: "It is with profound sadness and heavy hearts that the Betts family announce the peaceful passing of Forrest Richard 'Dickey' Betts (December 12, 1943 - April 18, 2024) at the age of 80 years old.
View this post on Instagram A post shared by Dickey Betts (@dickeybettsofficial)
"The legendary performer, songwriter, bandleader and family patriarch passed away earlier today at his home in Osprey, FL., surrounded by his family.
"Dickey was larger than life, and his loss will be felt world-wide.
"At this difficult time, the family asks for prayers and respect for their privacy in the coming days.
"More information will be forthcoming at the appropriate time."
Betts shared lead guitar duties with Duane Allman in the original Allman Brothers Band to help give the group its distinctive sound and create a new genre - Southern rock.
Acts ranging from Lynyrd Skynyrd to Kid Rock were influenced by the Allmans' music, which combined the blues, country, R&B and jazz with Sixties rock.
Founded in 1969, the Allmans were a pioneering jam band, trampling the traditional notion of three-minute pop songs by performing lengthy compositions in concert and on record.
In 1995 the band was inducted into the Rock and Roll Hall of Fame and won a Grammy Award for best rock instrumental performance for Jessica the following year.
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