It was the most watched television programme across all channels of 2015.
The peak at 8.55pm was watched by 14.5 million, beating last year’s figure of 13.3 million.
It was also the most watched non-sport programme on a Wednesday night since Christmas Day 2002.
Nadiya was crowned this year’s winner after 10 weeks and 30 challenges, including Black Forest Gateau, Spanische Windtorte, Flaouna and a wobbly Charlotte Russe.
The 30-year-old stay-at-home mother from Leeds beat fellow finalists Tamal Ray and Ian Cumming.
She went into the final as the bookmakers’ favourite, and delighted fans with her varied facial expressions that switched between delight, despair, shock, terror and joy as she baked her way to victory.
The Luton-born baker admitted to a lack of confidence before she went on the show. It was her husband and sister-in-law who persuaded her to apply.
She wowed the judges with her iced buns, millefeuille and patriotic Union Jack-themed wedding cake wrapped in a sari.
Nadiya said: “I went into the tent as the smallest baker at 4ft 11in but I walked out feeling a giant - almost as tall as my fellow baker, six-footer Mat Riley.”
Charlotte Moore, the controller of BBC One, said: “Event television at its best! The dramatic and emotional final of The Great British Bake Off rose to the occasion and brought the nation together on BBC One to become the most watched TV show of the year with 13.4 million viewers, and a peak audience of 14.5 million, smashing last year’s final.
“Congratulations Nadiya and the Bake Off team!”
The Great British Bake Off will return to BBC One next year.