Clips such as Cher Lloyd's first audition and One Direction's Judges Houses performance are among the most popular on the channel, picking up 25.8 million and 8.4m respectively.
© ITV
© ITV
The most-watched clip remains the bust-up between auditionees Ablisa, who ended up fighting onstage after an unsuccessful audition.
Ablisa's performance has had 27.3 million views worldwide.
Peter Cassidy, head of Fremantle Media UK Interactive, said: "How fitting that our X Factor YouTube channel hits one billion views just as the new series has kicked off. There have been so many great moments over the years and we look forward to creating many more this year with our partners Syco and ITV."
Theo Luke, head of Digital, Syco Entertainment, added: "We're delighted that The X Factor has hit this great milestone and that our shows continue to resonate with such a passionate worldwide audience."
Britain's Got Talent's YouTube channel passed the one billion mark earlier this month.
The most-watched X Factor YouTube videos are:
Ablisa (non-UK clip - 27.3m views)
Cher Lloyd auditions (non-UK clip - 25.8m)
Glee performing (UK clip - 8.8m)
One Direction Judges Houses clip (UK clip - 8.4m)
Janet Devlin's audition (UK clip - 8.2m)
Jade Richardson (UK clip - 7.4 m)
One Direction sing 'Only Girl in the World' (non-UK clip - 7.4m)
Cher Lloyd sings 'Stay' (UK clip - 7.3m)
One Direction sing 'Total Eclipse of the Heart' (UK clip - 7.1m)
Amelia Lily's audition (UK clip - 9.9m)
Cher Lloyd Bootcamp (non-UK - 6.7m)
