Ashleigh & Pudsey's win was seen by 11.38m (46.4%) between 7.30pm and 10pm, peaking with 13.8m in the last five minutes, and adding 496k (2.2%) on ITV1 +1.
Britain's Got More Talent bowed out with 1.59m (8.2%) immediately after the main show, grabbing an extra 128k on timeshift.
BBC One's The Voice - scheduled earlier to avoid a Got Talent clash - sunk to a new low of 5.64m (29.4%) at 6.10pm.
The National Lottery: In It To Win It (3.2m/13.7%) and Casualty (3.35m/13.1%) followed the singing contest, while The Cube took 2.97m (15.9%) for ITV1.
Keith Lemon's Lemonaid rumbled on with 1.78m (11.8%) at 5.45pm (+1: 122k). BBC One's screening of Madagascar logged 2.45m (18.4%).
Meanwhile, Top of the Pops earned BBC Two's best numbers with 1.42m (6.9%) at 10pm, while CSI: NY drew 1.02m (4.3%) an hour earlier at 9pm (+1: 142k).
Overall, ITV1 dominated primetime with 36.2% (+: 1.5%), ahead of BBC One's 20.2%. Channel 4 claimed third place with 5.6% (+1: 1%), followed by BBC Two's 4.9%, and Channel 5's 2.7%.
Scandinavian drama The Bridge continued with 705k (2.7%) and 639k (3.3%) on BBC Four between 9pm and 11pm.
Watch a video of Britain's Got Talent winner Ashleigh Butler talk about taking Pudsey to Hollywood below:
BARB ratings data supplied by Attentional