The opening show of the latest series of The Apprentice, starring tycoon Sir Alan Sugar, attracted 6.4 million viewers, overnight figures show.
Sir Alan is offering a six-figure salary for his new apprentice
The figure was more than double that achieved by Channel 4's Grand Designs Revisited, which was watched by 3.1m.
The BBC One show's opening episode saw the two teams of budding business moguls given two van-loads of fresh fish to shift by the end of the day.
ITV1 talent show drama Rock Rivals attracted 2.2 million viewers.
The Apprentice, which pits 16 contestants against each other as they try to win a contract working with Sir Alan, has gone from strength to strength since the first series began on BBC Two in 2005.
Nicholas de Lacy Brown was the first Apprentice contestant to be fired
It moved to BBC One last year.
"We're delighted series four of The Apprentice and You're Fired have kicked off with such a strong start, this year promises viewers more twists and turns than ever before," said a BBC spokeswoman.
The opening show is the best performing to date - series three launched with an audience of 4.5 million last year.
The Apprentice: You're Fired, which aired on BBC Two after the main show, had 2.6 million viewers.
The first candidate to be evicted this year was Nicholas De Lacy Brown, who is training to be a barrister.
He described his exit as a mixture of "disappointment and relief", adding that he and Sir Alan were like "chalk and cheese".
He said he wanted to be remembered "as the stylish one who wore sunglasses and a Saville Row three piece suit".