The episode, which introduced new judge Cheryl Cole as a replacement for Sharon Osbourne, averaged a hefty 10.19m (48.2%) for ITV1 between 7.30pm and 8.30pm. The figure is the show's best ever opening across its five series, up around 700,000 on the 9.5m audience for last year's premiere. The ratings are also more than triple that of karaoke gameshow Who Dares Sings!, which concluded its run with 3.09m (16.3%) in the 7pm to 8pm slot last week.
Following The X Factor at 8.30pm, a Coronation Street special episode of Who Wants To Be A Millionaire? entertained 6.47m (29.5%), while the preceding You've Been Framed! had 5.17m (27.7%) from 7pm. At 9.30pm, James Bond movie The World Is Not Enough appealed to 3.34m (16.6%).
BBC One put up an admirable fight during primetime, suffering relatively marginal week-on-week losses against the increased commercial competition. Before The X Factor, reality show Last Choir Standing had 4.97m (27.5%) from 6.15pm to 7.30pm, compared to 5m (26.5%) in a slightly later slot the week before.
National Lottery gameshow This Time Tomorrow was seen by 3.55m (17%) from 7.30pm to 8.20pm, a fall from 5.28m (25.6%), and at 8.20pm, a new episode of The Inspector Lynley Mysteries put in 3.88m (17.8%) over 90 minutes. The Last Choir Standing results show - shifted from Sunday night - pulled in 4.76m (23.9%) between 9.50pm and 10.15pm.
Channel 4's top performer was Big Brother, which rose 100,000 week-on-week to average 2.44m (11.3%) in the 9pm hour. An additional 231,000 (1.5%) watched on Channel 4+1. A repeat of Lee Evans XL Tour 2005 Live brought in 1.36m (7.7%) from 10pm and an extra 171,000 (1.7%) through timeshift. Earlier, the Porridge movie appealed to 1.25m (6%) between 7.15pm and 9pm.
On BBC Two, a Dad's Army repeat was popular with 1.53m (7.1%) then at 9pm, Have I Got Old News For You had 1.39m (6.3%). A repeat of Mock The Week was the day's best performing show for the channel, with 1.63m (7.8%) at 9.30pm. A terrestrial outing for BBC Four music documentary Pop Britannia also hit the right note, delivering 1.45m (8%) in the 10pm hour.
Five maintained a respectable audience with its Saturday night lineup of US imports, starting with audiences of 948,000 (4.4%) and 1.35m (6.2%) for an NCIS double bill at 7.55pm. At 9.50pm, CSI had 1.48m (7.9%) then an hour later, Law & Order: Criminal Intent was a hit with 1.02m (7.7%).
The popularity of The X Factor on ITV1 also spilled over to ITV2, where spinoff show The Xtra Factor - fronted by new presenter Holly Willoughby - had an all-conquering 1.23m (6.5%) between 8.30pm and 9.30pm. A further 69,000 (0.4%) watched on ITV2+1.
BBC Three had a decent night, meanwhile, starting with 247,000 (1.4%) for Olympic Football at 7pm then gradually rising throughout the night. At 8pm a Top Gear repeat drew 292,000 (1.6%) and at 9.05pm, another screening of the disaster flick Armageddon reached 536,000 (3.3%). A Family Guy double bill brought in 357,000 (3.5%) and 444,000 (5.6%) from 11.25pm.
The launch of the new football season boosted the audience for Sky Sports 1, with an average of 662,000 (7.2%) tuning in for live coverage of Arsenal vs West Brom between 12.30pm and 3pm. The following Soccer Saturday had 431,000 (4.1%) until 5.15pm, then live coverage of Bristol City vs Derby County managed 267,000 (1.8%) until 7.30pm.