The culinary TV hit, with judges Mary Berry and Paul Hollywood, was watched by 7.9 million viewers at its peak - its second highest ever audience.
That compares to 6.3 million who tuned in to the first episode of last year's series which was shown on BBC Two.
The show, which was watched by 2 million people when it launched in 2010, has become a huge hit for the corporation and transformed the careers of bakers Berry and Hollywood.
Claire Goodwin became the first contestant to leave the competition last night after breaking down over a Swiss roll.
The 31-year-old said she became "ridiculously worked up" over the cake and the pressure saw her burst into tears.
Mrs Goodwin said: "Getting myself ridiculously worked up about the Swiss roll was my worst moment. Why did I cry about a cake?
"I don't know why I did, but at the time you feel very passionate about it, and everything is magnified and seems more important than it is.
"But in real life, it is just a Swiss roll, and I had a bit of a laugh about it afterwards.
"My friend has got a mug made especially for me with the words 'I don't know why I am crying about cake... Claire Goodwin'."
Mrs Goodwin, a speech and language therapist from Cheshire, said her best moment was "pulling off" 36 chocolate cherry cakes even though they "exploded" and the judges labelled them "horrible".
The latest series has its youngest and oldest contestants, with 17-year-old Martha Collison combining baking with her AS-level exams and coursework, while 69-year-old Diana Beard is the oldest baker so far.
The series is presented by Sue Perkins and Mel Giedroyc.