That figure is 3.45m down on last year's show, when Cher Lloyd was voted off.
An additional 328k (1.4%) watched ITV1's two-hour extravaganza on timeshift, and The Xtra Factor managed to summon 465k (2.3%) for ITV2 from 10pm.
Following The X Factor, Piers Morgan's Life Stories lured 4.14m (19.7%) for an interview with Peter Andre, and an additional 280k (22%) caught up an hour later. Earlier on ITV1, This Is Justin Bieber pulled in 2.01m (8.1%).
BBC One's Strictly Come Dancing semi-final was the most-watched programme of the night, entertaining 10.96m (44.2%) from 6.30pm. Merlin took 5.53m (20.9%) at 8.15pm and Casualty hung on to 4.3m (16.2%) at 9pm.
BBC Two's evening was dominated by snooker coverage, which averaged 1.09m (4.2%).
In a poor evening for Channel 4, Tony Robinson's Gods and Monsters snared 620k (2.3%) and a further 115k (0.4%) on timeshift. A screening of Vicky Cristina Barcelona persuaded 470k (2%) to stay with the broadcaster at 9pm. Its timeshift rating was surprisingly strong, nabbing 113k (0.7%).
The 8pm episode ofNCIS had enough intrigue for 706k (2.7%) Channel 5 viewers, and Tommy Cooper's Christmas increased the audience to 1.16m (4.4%) at 9pm.
In a close-run race for the primetime crown, ITV just pipped BBC One with 27.9% to 26.2%. BBC Two trailed with 4.3%, and Channel 5 and Channel 4 earned 3.9% and 2.3% respectively.
BARB ratings data supplied by Attentional