A total of 15.9 million people saw Candice Brown win the contest on BBC One in October - 850,000 more than saw Nadiya Hussain win last year's final.
It is the highest audience since the London 2012 Olympics and Euro 2012.
If sporting events are excluded, it is the highest since 17.7 million watched Matt Cardle win The X Factor in 2010.
This year's Bake Off was the last full series to be on the BBC, although the corporation will screen two Christmas specials before the show moves to Channel 4.
The figures highlight why Channel 4 has paid a reported Â£25m per year for the rights.
The channel has not broken the 10 million mark since 2002 and the most-watched programme on Channel 4 so far this year is an episode of Gogglebox, which pulled in 5.8 million viewers in February.
But Channel 4 will need to win over Bake Off fans after hosts Sue Perkins and Mel Giedroyc left and one of the judges, Mary Berry, also decided to stay with the BBC.
Her judging partner Paul Hollywood will move with Bake Off to Channel 4. Programme makers Love Productions are yet to reveal who else will front the show.
Brown, 31, beat fellow finalists Andrew Smyth and Jane Beedle to be crowned winner of the seventh series of the amateur baking contest.
Source: Press Association/Barb
Follow us on Twitter @BBCNewsEnts, on Instagram at bbcnewsents, or if you have a story suggestion email entertainment.news@bbc.co.uk.
The final of this year's Great British Bake Off was the most watched TV programme in the UK since 2012, confirmed ratings figures show.