Channel 4 boss Mark Thompson has been appointed as the director general of the BBC, describing it as a "unique treasure of colossal value".
Grade [L] and Thompson are both former Channel 4 heads
Mr Thompson has resigned from his position as chief executive Channel 4 and replaces Greg Dyke, who left in the wake of the Hutton Report.
He spoke of his "joy and delight" at returning to the corporation.
But he could not confirm when he would take up his new post as he has to give six months' notice to Channel 4.
Asked how he would boost staff morale at the BBC in the wake of the Hutton Inquiry, he said they could be "very confident about its future", although there were "lessons to be learned from recent months".
"I worked for the BBC for 23 years and saw any number of crises and changes, journalistic and otherwise," he said.
"What I see when I look at the BBC is its scale and strength and high standards."
Mr Thompson had originally ruled himself out of becoming the new director general.
However, on Friday he said the job was "a one-of-a-kind opportunity and I couldn't let it pass".
"What's made the difference is what Sonia Gandhi called 'my inner voice'," he added, referring to Ms Gandhi's recent decision to turn down the role of Indian prime minister.
"My decision has been a difficult personal one, but it's the right thing for me."
However when pressed he would not discuss his strategic aims for the corporation or reveal his salary, although he did address the issue of the BBC's impending charter renewal and licence fee negotiations.
"People demand a great deal from the BBC, and we need a properly funded BBC to fulfil those demands," he said.
He also defended a comment he once made about the BBC's "jacuzzis of cash", saying it had been a tongue-in-cheek riposte to Greg Dyke's remark that Channel 4 was "awash" with money.
The director general was chosen by the board of governors, headed by chairman Michael Grade.
"We were impressed by Mark Thompson's analysis of the challenges facing the BBC, and by his track record," he said.
Mr Thompson's appointment was welcomed by the government and fellow broadcasters, including Culture Secretary Tessa Jowell, who praised his "experience, skills and enthusiasm".
The move was also hailed by his predecessor Greg Dyke.
"I welcome the appointment of Mark Thompson as Director General of the BBC," Mr Dyke told the ITV News Channel.
"He is a very talented executive and will do a very good job for the BBC."
Mr Thompson, 46, worked his way up the BBC, eventually becoming director of television, before leaving to take up the chief executive role at Channel 4 in 2001.
Since Mr Dyke resigned from the corporation in January, Mark Byford has been leading the BBC as acting director general.
Mr Thompson will be responsible for leading the BBC through the review of its current Royal Charter, which expires in 2006.
He will also have to guide the corporation through one of its rockiest periods in history following the criticism it received from Lord Hutton in his report into the death of scientist Dr David Kelly.
The inquiry concluded that an allegation in a report by ex-BBC reporter Andrew Gilligan, which accused the government of deliberately exaggerating the case for war, was "unfounded".
BBC Charter Renewal
Boost staff morale
Licence fee renewal
Modernise BBC regulation
Heal rift with government
Restore BBC's global reputation
Following the report Gavyn Davies stepped down as chairman, swiftly followed by Mr Dyke.