Introducing new judges Gary Barlow, Tulisa Contostavlos and Kelly Rowland, the eighth series of the talent show launched with 10.8m (45.7%), as well as a further 504k on ITV1 +1.
While slightly below the average of last year's record-breaking opener, this year's X Factor premiere peaked with a hefty 12.6m (51%) at 9pm.
Caroline Flack's The Xtra Factor, meanwhile, got off to a respectable start on ITV2, with 1.17m (5.4%) at 9.15pm (+1: 260k), making it the most-watched multichannel broadcast of the evening.
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Celebrity Big Brother held on to 2.74m (12.1%) for Channel 5 from 9.15pm, though just 159k (0.9%) joined Emma Willis on 5* for Celebrity Big Brother's Bit on the Side.
Being sandwiched between alpha male drama repeats would not have helped Celebrity Big Brother, as NCIS took just 657k (2.7%) at 8.05pm and Law & Order: SVU interested 926k (5.2%) from 10.15pm.
Over on ITV1 though, The X Factor was complemented by You've Been Framed, which kicked the night off with 3.53m (20.9%) at 6.30pm (+1: 212k), All Star Family Fortunes which started a new run with 5.63m (28.8%) at 7pm (+1: 162k) and a soap star special of Celebrity Who Wants to be a Millionaire? which logged 4.31m (19.4%) at 9.15pm (+1: 186k).
BBC One's night was far more low key, as 3.2m (17.1%) watched National Treasures: Book of Secrets from 6.20pm until 8pm, then The National Lottery: In It To Win It entertained 3.53m (16.1%), before Casualty and John Bishop's Britain slipped to 4.18m (17.5%) and 3.37m (15.2%) respectively.
Elsewhere, Die Hard saved Channel 4's blushes as 1.47m (7.3%) tuned in to the action thriller between 9pm and 11.30pm, while BBC Two's Proms coverage averaged 569k (2.6%) between 9pm and 11pm.
Overall, ITV1 topped primetime with 29.5% (+1: 1.3%), ahead of BBC One's 18%. For the third time in a row Channel 5 claimed third place with 6%, ahead of Channel 4's 5.3% (+1: 0.8%) and BBC Two's 4.6%.
BARB ratings data supplied by Attentional