On April 1, before performing his self-arranged rendition of Dolly Parton's "Little Sparrow" on American Idol, Cook responded to Ryan Seacrest in the interview session, revealing that his performance of "Eleanor Rigby" was based on Neil Zaza's and Doxology's versions.He also reiterated the credits of Whitesnake and Chris Cornell.The song also reached #61 in the UK due to downloads alone.Cook has also signed an endorsement deal with Skechers that will run through December 2009.Cook originally did not plan to try out for the show.He came to the auditions initially to support his younger brother Andrew (who did not make it to Hollywood) and then, at his brother's urging, David tried out himself.
Prior to Idol he released an album entitled Analog Heart, and his post-Idol self-titled album, produced by Grammy-winning producer Rob Cavallo, was released on November 18, 2008 and has since been certified Platinum by the RIAA. David's eldest brother, Adam, battled brain cancer for 11 years until his death on May 2, 2009. He began singing in second grade, when his elementary school music teacher gave him a solo in a school choir performance.
After losing interest in the sport due to injury, he focused more on music.
He earned a theater scholarship to the University of Central Missouri, but he abandoned theater after two semesters, graduating from the school in 2006 with a degree in graphic design.
At the 2008 Teen Choice Awards, Cook won the Best Reality/Variety Star award, alongside Lauren Conrad of The Hills.
Cook's photo is also featured on the cover of The World Almanac and Book of Facts 2009, along with President Barack Obama and Senator John Mc Cain.