John Whaite's victory in the competition attracted an average audience of 6.54m (25.3%) to BBC Two in the 8pm hour.
Judges Mary Berry and Paul Hollywood crowned the law graduate above Digital Spy favourite James Morton as well as Brendan Lynch.
Way above the channel's average for the slot, many expect The Great British Bake Off to be promoted to BBC One following its unexpected rise in popularity.
Bake Off's figures are all the more impressive considering the stiff competition from other channels - Holby City drew 5.08m (19.6%) for BBC One, while 4.24m (17%) watched ITV1's build-up to the eventually postponed England v Poland football match.
Probably thanks to the called-off England game, many switched over to The Paradise on BBC One, which soared to 5.15m (22%) in the 9pm hour. Doc Martin, pencilled in at the last minute by ITV as FIFA prolonged its decision about whether to postpone, managed 1.8m (7.8%), and was beaten by Ian Hislop's Stiff Upper Lip (2.37m/10.2%) on BBC Two.
Elsewhere, Double Your House For Half the Money took 1.24m (4.8%) for Channel 4 at 8pm (+1: 268k/1.1%), then Jewish Mum of the Year interested 1.19m (5.1%) at 9pm (+1: 181k/1.1%), and Fresh Meat amused 870k (5.1%) at 10pm (+1: 111k/1.2%).
Meanwhile on Channel 5, Person of Interest mustered 1.26m (5.4%) in the 9pm slot, adding 109k (0.7%) on +1.
Overall, BBC One led primetime with 23.2%, ahead of ITV1's 15.2% and BBC Two's 12.7%. Channel 4 was pegged back to fourth with 4.4% (+1: 0.8%), above Channel 5's 3.6% (+1: 0.3%).
BARB ratings data supplied by Attentional
Digital Spy breakfast show - watch Anna Williamson discuss the day's biggest stories including Girls Aloud, X Factor and The Great British Bake Off: