As a session musician, Leavell has performed on every Rolling Stones studio album released since 1983 with the exception of Bridges to Babylon (1997).

He has also toured and recorded with Eric Clapton, George Harrison, David Gilmour, Gov't Mule, Train, and John Mayer.

The Misfitz played a steady gig at the YMCA every Friday night, and eventually were the band for a Saturday morning television show, Tuscaloosa Bandstand.

After the breakup of the Misfitz, Leavell did session work, and found himself on his first gold record, a single by Freddie North called "Don't Take Her She's All I've Got".

When Taylor had a falling out with his manager and the founder of Capricorn, Phil Walden, and quit touring, Leavell found himself playing with Dr. John.

After The Allman Brothers Band disbanded in May 1976, the trio added guitarist Jimmy Nalls and set about touring behind the moniker Sea Level, derived from Leavell's first initial and last name.

Although the group received good critical notices, and is viewed positively in retrospect by Leavell, it was unable to garner a recording contract.

After Stewart's death in 1985, Leavell occupied the role of the group's keyboardist by himself, with the exception of the addition of Matt Clifford on the Steel Wheels record and tour.

[7] In addition to his work with The Rolling Stones, Leavell has worked with George Harrison, Eric Clapton, Gov't Mule, Train, Tinsley Ellis, The Black Crowes, The Fabulous Thunderbirds, Montgomery Gentry, John Mayer, Miranda Lambert, Blues Traveller amongst many others in the studio and on the road, in addition to recording five solo albums.

In an April 2007 radio interview on WOR-AM, Leavell said his favorite contributions to songs in his career were "Jessica" with The Allman Brothers Band, "Old Love" on Eric Clapton's Unplugged, Out of Tears on The Rolling Stones' Voodoo Lounge, and Drops of Jupiter by Train.

Since 2001, he has performed as a guest pianist at more than a dozen Allman Brothers Band concerts, including multiple shows at the Beacon Theatre in New York City.

Leavell and several other well-known Alabama musicians (including Wayne Perkins, Chuck Tilley, Charlie Hayward, and Kelley O'Neal) donated their time for this project.

The 2008 BAMA Awards ceremony was held at the Alabama Jazz Hall of Fame (in the historic Carver Theatre in the Birmingham Civil Rights District).

Leavell performed at this ceremony accompanied by the Alabama Jazz Hall of Fame All-Stars directed by Ray Reach.

The film, featuring Mick Jagger, Keith Richards, Charlie Watts, Ronnie Wood, David Gilmour, Dickey Betts, Warren Haynes, John Mayer, Julian Lennon, Billy Bob Thornton, Charlie Daniels, Bonnie Raitt, Bruce Hornsby, Chris Robinson, Miranda Lambert, Eric Church, Mike Mills, Pat Monahan, John Popper, and Lee Ann Womack among others will be available for streaming beginning December 1, 2020.

Leavell and Joel Babbit are the co-founders of The Mother Nature Network, an environmental news and information website that launched in January 2009.

[17] In response to requests from fans and teachers alike, Leavell and Howard Citron co-founded IROCKU, a rock and blues piano instructional website that launched in June 2011.

[19] Solo albums Alex Taylor Sailcat Gregg Allman The Allman Brothers Band Chuck Berry Dickey Betts Aretha Franklin Sea Level Duke Jupiter The Rolling Stones The Black Crowes Eric Clapton Gov't Mule Train John Mayer David Gilmour George Harrison Col. Bruce Hampton and the Aquarium Rescue Unit