Peter Mandelson, who was twice forced to resign from Tony Blair's cabinet, has made a remarkable comeback after being drafted into British Prime Minister's Gordon Brown's cabinet.
Mr Mandelson says he is surprised but proud that Mr Brown, has appointed him as business secretary.
The EU trade commissioner joked in Downing Street, London on Friday that his appointment was "third time lucky".
The two men have put aside a long-standing enmity towards each other to work together.
The Prime Minister and Labour Party leader said he needed "serious people for serious times" and Mr Mandelson had unrivalled experience in global trade.
He was dubbed by the press as the "Prince of Darkness" for his spin doctor skills and Machiavellian ways in reshaping the Labour Party into the electable force that has been in power since 1997.
Mr Brown said he wanted to "reinvent government" to cope with the new challenges of financial instability, oil price rises and food price rises.
"He has built up a reputation over the last few years as someone who can get things done," said Mr Brown.
"Whatever the ups and downs have been in the past, everybody has got to come together and make sure that as a nation we come through this successfully."
Mr Mandelson, the former Northern Ireland and trade and industry secretary, said he was not expecting to be asked but was looking forward to the challenge.
He has a tough task to help Labour gain ground on the opposition. The latest political survey showed the Conservatives still far ahead of Labour following the annual party conference season, which concluded on Wednesday.
The poll put the centre-right Conservatives on 42%, Labour on 30%, and the centre-left Liberal Democrats on 17%.
Former home secretary David Blunkett described Mr Mandelson's appointment as a "masterstroke" and believed it would unite the government.
"It is embracing someone who, in the past, had been seen as being very close to Tony Blair, so it's an inclusive measure," he said.
But left wing Labour MP John McDonnell said he was "absolutely gobsmacked": "This is an extraordinary step backwards into the worst elements of the Blair era, to reinstate possibly the most divisive figure in Labour's recent history."
The reaction in Britain's press has been generally critical.
"His feud with Gordon Brown was so bitter that for years they barely spoke. So it shows the PM's desperation," said The Sun, Britain's biggest-selling daily.
The Daily Mail said on its front page: "Arise Lord Sleaze", while inside, columnist Richard Littlejohn called Mandelson an "odious, discredited creep... the most malignant tumour on Britain's body politic".
The quality press concluded that it was a high-risk gamble with Brown staking his premiership on a dangerous figure.
But The Guardian said it was "one of the most brilliant coups" of Brown's career.
In other moves Labour veteran Margaret Beckett gets housing and Ed Miliband heads up a new climate and energy department.
Geoff Hoon replaces Ruth Kelly, whose resignation as transport secretary triggered the reshuffle.
Immigration minister Liam Byrne has been promoted to the new role of policy coordinator, not a full cabinet role but he will attend cabinet meetings. Mrs Beckett will replace Caroline Flint as housing minister. Ms Flint will go to the Foreign Office as Europe minister.
Defence Secretary Desmond Browne is to leave the government after turning down two job offers from Mr Brown.
Former agriculture minister, and close Gordon Brown ally, Nick Brown returns as chief whip, to replace Mr Hoon. Leader of the House of Lords, Baroness Ashton, will replace Mr Mandelson in Brussels.