A new episode of the show, which featured the controversial exit of Zimbabwe-born singer Gamu Nhengu at the Judges' Houses stage, averaged 13.33m (45.9%) for ITV1 from 7.45pm, while 748k (2.6%) watched on ITV1 HD.
After The X Factor, new period drama Downton Abbey pulled in 8.54m (32.2%) on ITV1 in the 9pm hour, up 1.15m week-on-week. An additional 244k (0.9%) watched the show in HD.
The two programmes enabled ITV1 to obliterate BBC One in primetime, after the Antiques Roadshow and Inspector George Gently grabbed respective audiences of 6.15m (22.1%) and 4.87m (17.6%) from 7.30pm.
Earlier on ITV1, The Cube appealed to 5.71m (24.5%) from 6.45pm and 157k (0.7%) on ITV1 HD, but it was beaten by Countryfile, which brought in 6.37m (28%) on BBC One from 6.30pm and 148k (0.7%) on BBC HD.
Coverage of the Ryder Cup mustered 1.79m (6.3%) on BBC Two between 7.30pm and 9.30pm, while 142k (0.5%) watched in HD.
Also on BBC Two, documentary Can England Win The World Cup? took 1.3m (5.2%) from 9.30pm, before Match Of The Day 2 scored with 2.67m (17%) from 10.15pm.
Channel 4's The Genius Of British Art brought in 640k (2.6%) in the 8pm hour and 47k (0.2%) on timeshift, then a screening of 27 Dresses secured 1.11m (4%) from 9pm and 593k (2.6%) on Channel 4 +1.
On Five, screenings of Charlie's Angels: Full Throttle and Ghost Rider grabbed respective audiences of 765k (2.9%) and 1.57m (7%) from 8pm.
Overall, ITV1 owned primetime with 32.5% (HD: 1.4%) against BBC One's 20.4%. BBC Two came in third with 7.3%, followed by Five with 4.7% and Channel 4 with 4% (+1: 1.3%).
Elsewhere, The Xtra Factor took the biggest multichannel audience of the night, after 1.01m (3.8%) watched on ITV2 in the 9pm hour and 138k (0.7%) tuned in an hour later.
BARB ratings data supplied by Attentional