His audition failed to impress two of the judges, Sharon Osbourne and Louis Walsh, who thought he lacked the motivation and confidence to succeed but the third, Simon Cowell, asked Brookstein to return the following day and sing again.
He reached the grand final on 11 December 2004 alongside G4 and won, despite him mixing up words and lines in his winner's song and a controversial outburst against him from Osbourne.
[6] After winning The X Factor, Brookstein was signed to the Sony BMG record label through which he released his first single, a cover of Phil Collins' 1984 power ballad "Against All Odds", on 20 December 2004.
[10] Brookstein has publicly feuded with Simon Cowell and The X Factor, claiming "there is absolutely no way he would want me within 100 miles of him"[11] and admitting spending years feeling bitter about the way he was treated on the show.
[13] In June 2007, Brookstein appeared on the P&O Portsmouth to Bilbao car ferry, alongside The X Factor series 2 alumni Chico Slimani and Journey South.
[18] Despite Brookstein's bitterness towards The X Factor, he signed up to critique the show weekly on London 24 in 2010,[19] where he labelled the judges "ridiculous" and questioned the standards of several of the finalists,[20] including One Direction band member Louis Tomlinson, and the vocal coach.