The 13th series of the reality competition attracted an average rating of 11.54 million (45.5%) at 9pm, with an added 386,000 (2.4%) on +1, and peaked at 12.9m viewers.
This is up from last year's ratings of 10.26m, and eclipses its best ever opening figures from 2011's launch.
Peter Fincham, Director of Television at ITV, said: "A peak audience of nearly 13 million viewers in its 13th series is fantastic - a real testament to the continuing power of this brilliant show."
Earlier, The X Factor was up by around 50k from last Sunday to 8.99m (33.0%) at 8pm (221k/0.8%).
On BBC One, Strictly Come Dancing dropped around 800k viewers to 9.56m (34.7%) at 7pm. The Paradise lost around 500k to 4.19m (15.4%) at 8pm. Britain and the Sea brought in 2.71m (10.1%) at 9pm.
BBC Two's Great Continental Rail Journey was seen by 2.37m (8.7%) at 8pm, while Africa 2013 gathered 1.29m (4.8%) at 9pm.
On Channel 4, documentary Queen Victoria and the Crippled Kaiser interested 1.42m (5.2%) at 8pm (271k/1.0%). Homeland thrilled 1.61m (6.0%) at 9pm (120k/0.6%).
Channel 5's broadcast of Rush Hour 2 entertained 863k (3.1%) at 7.30pm (140k/0.5%), while The Book of Eli was seen by 893k (4.0%) at 9pm (131k/0.9%).
On BBC Three, Doctor Who's Greatest Monsters and Villains Weekend peaked at 695k (2.6%) at 9pm. Family Guy amused 780k (3.2%) at 10pm.
ITV2's I'm a Celebrity, Get Me Out of Here Now! launched with 1.07m (7.8%) at 10.30pm.
BARB ratings data supplied by Attentional