Dickey Betts, a honky-tonk hell raiser who, as a guitarist for the Allman Brothers Band, traded fiery licks with Duane Allman in the band’s early-1970s heyday, and who went on to write some of the band’s most indelible songs, including its biggest hit, “Ramblin’ Man,” died on Thursday at his home in Osprey, Fla. He was 80.

His death was announced on social media by his family. His manager David Spero said in a statement to Rolling Stone magazine that the cause was cancer and chronic obstructive pulmonary disease.

Despite not being an actual Allman brother — the band, founded in 1969, was led by Duane Allman, who achieved guitar-god status before he died in a motorcycle accident at 24, and Gregg Allman, the lead vocalist, who got an added flash of the limelight in 1975 when he married Cher — Mr. Betts was a guiding force in the group for decades and central to the sound that, along with the music of Lynyrd Skynyrd, came to define Southern rock.

Although pigeonholed by some fans in the band’s early days as its “other” guitarist, Mr. Betts, whose solos seemed at times to scorch the fretboard of his Gibson Les Paul, proved a worthy sparring partner to Duane Allman, serving more as a co-lead guitarist than as a sidekick.

With his chiseled features, Wild West mustache and gunfighter demeanor, Mr. Betts certainly looked the part of the star. And he played like one. Nowhere was that more apparent than on the band’s landmark 1971 live double album, “At Fillmore East,” which was filled with expansive jams and showcased the intricate interplay between Mr. Betts and Mr. Allman. It sold more than a million copies.

“The second half of ‘At Fillmore East’ is as vivid and exhilarating as recorded rock has ever been,” Grayson Haver Currin of Pitchfork wrote in a 2022 appraisal.

A centerpiece of the album was “In Memory of Elizabeth Reed,” a haunting, jazz-influenced instrumental written by Mr. Betts whose title was taken from a headstone at a graveyard in the band’s hometown, Macon, Ga. That track’s “textural interplay,” Mr. Currin continued, “resembles Miles Davis’s then-new electric bands, organ and guitar oozing into one another like melting butter and chocolate.”

“Duane and I had an understanding, like an old soul kind of understanding of let’s play together,” Mr. Betts said in a 2020 interview with The Sarasota Herald-Tribune in Florida. “Duane would say, ‘Man, I get so jealous of you sometimes when you burn off and I have to follow it,’ and we would joke about it. So that’s kind of Duane and mine’s relationship. It was a real understanding. Like, ‘Come on, this is a helluva band, let’s not hot dog it up.’”

That brilliant guitar dialogue ended in Macon on Oct. 29, 1971, when Mr. Allman lost control of his motorcycle after swerving to miss a truck and died of extensive internal injuries sustained in the crash (Berry Oakley, the band’s bassist, was killed a year later in a motorcycle accident just a few blocks from the site).

Mr. Betts took over as the band’s leader and featured guitarist when the Allman Brothers Band regrouped to complete its next album, “Eat a Peach.” Released in 1972, it was critically acclaimed and vaulted to No. 4 on the Billboard charts. Among the album’s most memorable tracks was Mr. Betts’s sunny country-inflected number “Blue Sky,” which lived on as a rock classic.

The band reached new commercial heights with its follow-up the next year, “Brothers & Sisters,” which contained two of Mr. Betts’s signature songs: “Ramblin’ Man,” which rose to No. 2 on the Billboard Hot 100, and the upbeat instrumental “Jessica.”

“Ramblin’ Man,” which Mr. Betts sang, is a carefree tale of an unfettered life on the open road. “I guess the song is more or less autobiographical,” he said in a 1973 interview with the future movie director Cameron Crowe, who was then a writer for Rolling Stone. “Not right down to the point, but overall it’s a pretty true song. There’s a lot of things I wish I could say in my songs that I can’t.”

He apparently made an impression on Mr. Crowe. His horseshoe mustache and bad-boy swagger became the inspiration for Billy Crudup’s rock-star character in Mr. Crowe’s quasi-autobiographical 2000 film, “Almost Famous.” As Mr. Crowe told Rolling Stone in 2017: “Dickey seemed like a quiet guy with a huge amount of soul, possible danger and playful recklessness behind his eyes. He was a huge presence.”

Forrest Richard Betts was born on Dec. 12, 1943, in West Palm Beach, Fla., one of three children of Harold and Sarah Betts. Growing up on the Gulf Coast in Bradenton, near Tampa, he learned an early appreciation of music from his father, a fiddler, and started playing ukulele at 5.

He graduated to guitar and formed his own band in his teens. In 1967, he formed another band, the Second Coming, with Mr. Oakley. They later jammed with Duane Allman, who eventually invited them to join his new band.

After the triumph of “Brothers & Sisters,” which topped the Billboard 200 for five weeks in 1973, the Allman Brothers Band started to fray. Gregg Allman started a side solo career, as did Mr. Betts, who released an album, “Highway Call,” in 1974.

Along the way, the band’s outsize drug and alcohol use was becoming an increasing problem, as was the internal pressures that came with success. The band splintered in 1976 after Gregg Allman testified against the band’s security man in a federal drug case; Mr. Betts vowed never to work with Mr. Allman again.

Still, he did. Although Mr. Betts continued with two side ventures, the band Great Southern and the Dickey Betts Band, in 1979 the Allman Brothers Band released a comeback album, “Enlightened Rogues,” and would continue to tour and record, despite lengthy hiatuses, until 2000. That year, the group fired Mr. Betts, citing “creative differences” — while also alluding to continuing struggles with substance abuse, which he denied.

By that point Mr. Betts had been through plenty of struggles with drugs and alcohol, as well as multiple arrests, including a much-publicized incident in 1996, in which he was accused of aiming a .44 Magnum handgun at his wife, Donna, during a quarrel over his drug use and charged with aggravated domestic assault. The charges were dropped after he agreed to check himself into a rehab facility.

In addition to his wife, Mr. Betts’s survivors include his daughters, the country artist Kimberly Betts, Christy Betts and Jessica Betts, as well as his son, Duane Betts, who made appearances with the Allman Brothers Band in the 1990s and later joined Great Southern.

Despite undergoing brain surgery in 2018 after a fall at home, Mr. Betts released live albums with the Dickey Betts Band in both 2018 and 2019.

He received notable recognition when Bob Dylan referenced him in “Murder Most Foul,” Mr. Dylan’s 2020 opus about the assassination of President John F. Kennedy. It contains the line “Play Oscar Peterson, play Stan Getz/Play ‘Blue Sky,’ play Dickey Betts.”

When friends called him about the shout-out, Mr. Betts was deeply honored, he said in a recent interview, but also embarrassed. “I would say, ‘Well, he just used me because it rhymes with Getz.’”