Lewis was born in Vermont to hippie parents living in a log cabin. When his parents split up, he moved with his father to Springfield, Massachusetts, where he attended high school.
In July 2010, Lewis finished recording a country music EP entitled Town Line that was released March 1, 2011 on Stroudavarious Records. It features seven tracks including three versions of the first single "Country Boy" featuring George Jones, Charlie Daniels, and Chris Young, as well as the songs "Massachusetts", "Vicious Circles", "The Story Never Ends", and a re-recording of "Tangled Up in You" originally from The Illusion of Progress. Lewis said in a July 2011 interview that he was introduced to country music as a child by his grandfather, but his interest was recently rekindled when he toured with fellow rock turned occasional country singer Kid Rock.
Lewis released his first full solo album, The Road, in November 2012. Its debut single, "Endless Summer", has also made the country charts. Lewis wrote every song on the 10 track collection, except for "Granddaddy's Gun" which was penned by Dallas Davidson, Rhett Akins and Bobby Pinson, marking the first time Lewis has recorded outside material for an album. In an interview with Broadway's Electric Barnyard, Lewis said he recorded "Granddaddy's Gun" as both a compliment to a friend, and because he was pressed for time.
Lewis wrote songs for his second solo album whilst touring in support of The Road, often performing the unreleased material in his live sets. The album, dubbed Sinner, was mostly recorded in a single 18 hour session, with many tracks done in one take. Aaron's daughter Zoe also provides guest vocals on one song.
Lewis was featured on the song "No Sex" by Limp Bizkit on their album Significant Other. He was also featured on a remix of the song "Crawling" on Linkin Park's first remix album Reanimation (titled as "Krwlng" on the remix album). He contributed vocals to the song "Follow" by Sevendust from Animosity, and to the songs "Bleed" and "Send in the Clowns" by the band Cold from 13 Ways to Bleed on Stage. He's also featured on Jimmie's Chicken Shack's song "Falling Out", the only single off their 2004 album re.present. In December 2010 while promoting his Town Line album Lewis collaborated with Corey Taylor for a one-night-only acoustic duet show covering songs such as Pearl Jam's "Black", Pink Floyd's "Comfortably Numb", and Alice in Chains' "Down in a Hole". Lewis told Broadway's Electric Barnyard that he's open to collaborating with anyone. When asked specifically about Jason Aldean, whom he shouts out in "Endless Summer", Lewis said, "Yeah."