He played several instruments during his performances, including the acoustic guitar, the electric guitar, the keyboard, and the piano.
His performance of "To Make You Feel My Love" as part of the Top 11 earned praise from the judges, with Simon Cowell commenting, "I am genuinely beginning to think you have a shot of doing well in this competition." In the finals, he performed his own arrangement of "Ain't No Sunshine" on a keyboard, with a few musicians on stage, which earned praise from the judges.
Allen's homecoming parade was greeted by a crowd estimated to be greater than 20,000.
Allen performed at three concerts in Little Rock and Conway, Arkansas, playing many of his popular songs during the competition, including "Man in the Mirror", "Ain't No Sunshine", "Falling Slowly" and "She Works Hard for the Money" at the venues, as well as "Come Together" at the studio of local Fox affiliate KLRT-TV.
He worked as a shoe salesman at a sporting goods store during the day to make ends meet and continued playing gigs in Little Rock and Fayetteville at night.
In the early stages of the season, he was among the finalists (along with Allison Iraheta) that received the least amount of screen time.
Allen's Idol coronation song, "No Boundaries" and his version of "Heartless" both charted within the Top 20 of the Billboard Hot 100. Additionally, he taught himself to play the guitar at age 13, and also plays the piano.
Allen's post-Idol self-titled album was released on November 17, 2009, by Jive Records. His musical influences, as stated in his Idol confessionals, include the Beatles, Jamie Cullum, Jason Mraz, Pat Monahan, John Mayer and Michael Jackson.
During the final results show, he performed a duet with Keith Urban, singing Urban's single "Kiss a Girl", as well as a series of medleys with his fellow Season 8 contestants.
Before the results were announced, Allen performed "We Are the Champions" with eventual runner-up Adam Lambert and Brian May and Roger Taylor of Queen.
However, during the Top 3 results show, host Ryan Seacrest had revealed that the margin between Allen and Lambert was fewer than a million votes.