"I have decided that the honourable thing to do is to step down," George Entwistle (L) announced late Saturday
The BBC was in turmoil on Sunday after its director-general dramatically quit over a broadcast by the British broadcaster's flagship news show that wrongly accused a politician of child sex abuse.
George Entwistle's departure -- after just two months in the job -- plunges the BBC into fresh crisis after it was engulfed by a scandal surrounding Jimmy Savile, the late BBC star now alleged to have been a prolific sex offender.
"The wholly exceptional events of the past few weeks have led me to conclude that the BBC should appoint a new leader," Entwistle said in a televised statement outside the broadcaster's London headquarters late Saturday.
"To have been the director-general of the BBC even for a short period, and in the most challenging of circumstances, has been a great honour."
The 50-year-old's leadership is the shortest in the BBC's history.
Entwistle announced his resignation the day after the BBC's flagship news programme Newsnight was forced to apologise for wrongly implicating a senior Conservative party figure in abuse at a Welsh children's home in the 1970s.
The director-general said that although he was not aware of last week's Newsnight report before it was aired, quitting was "the honourable thing to do" since he was the BBC's editor-in-chief, and ultimately responsible for all output.
He had earlier said he would not resign unless asked to do so by the corporation's governing body, the BBC Trust.
"I am doing the right things to try and put this stuff straight," he insisted in an interview on BBC radio.
Tim Davie, a former Pepsi executive who is currently the BBC's director of audio and music, will take over immediately as acting director-general.
Britain's Sunday newspapers described the crisis as one of the deepest in the BBC's 90-year history.
The Mail on Sunday condemned Entwistle as the "DG who turned a blind eye to (the) BBC meltdown -- and paid the ultimate price", while the Independent on Sunday's verdict on Entwistle was: "Out of touch. Out of depth. Out of a job".
Earlier on Saturday, Entwistle had said it was "fundamentally wrong" of Newsnight to air an interview with a man claiming he was repeatedly abused at a children's home in the 1970s by a senior Conservative politician.
The programme last week did not identify the politician, but he was widely named on the Internet as former Tory party treasurer Alistair McAlpine, a former aide to Margaret Thatcher.
McAlpine went public on Friday to strongly deny the allegations, and in a serious blow to Newsnight's prestigious reputation his accuser Steve Messham then retracted his claims, saying McAlpine was a victim of mistaken identity.
Entwistle, who first joined the BBC in 1989, was only installed as its director-general on September 17 and had spent his short time at the top dealing with the fall-out from the Savile scandal.
Both Newsnight and Entwistle have come under scrutiny after it emerged that the programme had last year dropped an investigation into the Savile abuse claims.
As director of BBC Vision at the time, Entwistle was in charge of all television output when the Savile report was axed. He also came under fire for deciding to proceed with a Christmas tribute to the late DJ.
Entwistle, who edited Newsnight himself a decade ago, admitted on Saturday that the corporation faced a "crisis of trust" over the two sex abuse rows.
Standing alongside Entwistle as he made his resignation statement, BBC Trust chairman Chris Patten said it was "one of the saddest evenings of my public life".
The former Hong Kong governor said: "At the heart of the BBC is its role as a trusted global news organisation.
"As the editor-in-chief of that news organisation George has very honourably offered us his resignation because of the unacceptable mistakes -- the unacceptable shoddy journalism -- which has caused us so much controversy."
Culture minister Maria Miller welcomed Entwistle's decision to quit.
"It is a regrettable but the right decision," she said. "It is vital that credibility and public trust in this important national institution is restored."
But Newsnight anchor Jeremy Paxman, famed in Britain for his forthright style, said Entwistle had been "brought low by cowards and incompetents".
"I had hoped that George might stay to sort this out. It is a great pity that a talented man has been sacrificed," he said.