The BBC Two cookery spinoff averaged 3.78m (15.6%) and peaked with over 4.5m as two winners were announced for the first time in the franchise's history.
With The Professionals now in its fourth run, having started in 2008, yesterday's finale achieved a new all-time high, beating the previous 3.6m record set only on Tuesday.
BBC Two's MasterChef earned a surprise victory over BBC One's Young Apprentice, which retained a steady if unspectacular 3.18m (13.1%) in the 8pm slot for series three's penultimate episode.
Airing in a quieter 9pm hour, Britain's Hidden Housing Crisis (3.68m/17%) led the way for BBC One, Pensioners Behind Bars interested 3.44m (15.9%) on ITV1 (+1: 288,000), Jamie and Jimmy's Food Fight Club logged 1.36m (6.3%) for Channel 4 (+1: 146k), The Hour hooked 1.17m (5.4%) for BBC Two, and 1m (4.6%) watched Channel 5's Cowboy Builders.
Overall, ITV won primetime with 20.1% (+1: 0.9%), beating BBC One's 19.3%, BBC Two's 8.3%, Channel 4's 4.7% (+1: 0.9%), and Channel 5's 3.6% (+1: 0.2%).
The Big Bang Theory extended its domination over Celebrity Juice in the multichannel world, soaring to 1.41m (5.6%) at 8pm on E4 (+1: 435k) while A Celebrity Juicemas Carol attracted 1.12m (6.7%) at 10pm on ITV2 (+1: 148k).
BARB ratings data supplied by Attentional