The sixth series of British television music competition The X Factor started on ITV on 22 August 2009 and was won by Joe McElderry on 13 December 2009.

Cheryl Cole emerged as the winning mentor for the second consecutive year, the first time in the show's history that a mentor has won back-to-back series. The show was presented by Dermot O'Leary, with spin-off show The Xtra Factor hosted by Holly Willoughby on ITV2.

Public auditions by aspiring singers began in June 2009 and were held in five cities across the UK. Judges Simon Cowell, Dannii Minogue, Louis Walsh, and Cheryl Cole returned to judge the contestants, with auditions being held in front of a live audience for the first time. Following initial auditions, the "Boot camp" stage took place in August 2009, where the number of contestants was narrowed down to 24. The 24 contestants were split into their categories, Boys, Girls, Over 25s and Groups, and given a judge to mentor them at the "Judges' houses" stage and throughout the finals.

During "Judges' houses", the 24 acts were reduced to twelve, who went on to the live finals, with one act being eliminated each week by a combination of public vote and judges' decision until a winner was found. The live shows started on 10 October 2009. The acts performed every Saturday night with the results announced on Sundays. This was change of format from previous series in which the results were announced later on the Saturday evening.

The winner's single for this series was a cover version of Miley Cyrus's "The Climb".