Willmon was raised on a ranch near Afton, Texas. By his second year in college, he dropped out to join a bluegrass band. In 1995, he moved to Nashville to start a songwriting career, and by 1998 he had a song-publishing contract with Sea Gayle Music.

One of his first cuts as a songwriter was "It Doesn't Mean I Don't Love You". This song was recorded by the short-lived duo McHayes (which comprised 1990s country singer Wade Hayes and fiddler Mark McClurg), and reached #41 on the country charts in 2003.

Willmon signed with Columbia Records in 2004. His self-titled debut album was released that year, and it produced four singles. The first of these was "Beer Man", which peaked at #30 on the country charts.

Following it were "Dixie Rose Deluxe's" at #36, "Home Sweet Holiday Inn" at #49, and finally "The Good Life" at #38. A second album, A Little More Livin', followed in 2006. Although its lead-off single "On Again Tonight" became his highest chart entry at #27, the follow-up "So Am I" peaked at #59, and Willmon exited Columbia's roster.

Willmon signed with Compadre Records in 2007. His third album, Broken In, was released on February 26, 2008. The album produced three singles in "There Is a God", the title track, and "Cold Beer and a Fishing Pole", though none of these entered the charts.

In early 2008, he also made his acting debut in the film Palo Pinto Gold, a cowboy film also starring Roy Clark and Mel Tillis He also had another chart success as a songwriter in early 2008, having co-written Montgomery Gentry's Number One hit "Back When I Knew It All".

He also co-wrote a song entitled "Better Than This", recorded by Brad Paisley on his 2007 album, 5th Gear.