The national interest must come before party politics, the prime minister has said of his controversial appointment of Peter Mandelson to the cabinet.
Mr Mandelson, considered divisive by many Labour MPs, was drafted back to the cabinet for an unprecedented third time in a major cabinet reshuffle.
Schools Secretary Ed Balls told Sky News Mr Brown had taken "a risk" - but said it was the right decision.
He insisted the new business secretary was "devoted" to public service.
Mr Balls said: "Of course it's a risk, but at the same time, it's also a great opportunity for our country and our government.
"Gordon Brown looked at this carefully and he decided it was worth that risk and I think that was the right thing to do."
Mr Brown said he wanted the best talent to tackle the economic crisis.
But some MPs have not welcomed Mr Mandelson's return - one cabinet member is thought to have tried to prevent it.
Mr Mandelson, who for the last four years has been an EU trade commissioner replaces John Hutton in his new position.
The move triggered controversy among MPs not only because Mr Mandelson has twice been forced to resign, but because he and the prime minister are known to have previously been locked in a long-running feud.
But speaking outside Downing Street earlier, Mr Brown said: "I think the national interest comes before any party politics and any personality politics.
"Today we see a Labour government which is determined to work with business and to work with the rest of the community to deal with the real challenges that we face as a result of these global changes."
Mr Brown said he had put together a cabinet that could draw on expertise from across the business sector and the European Union.
Earlier, the prime minister's decision was also praised by Ed Miliband, another beneficiary of the reshuffle, having been appointed as head of the new Department for Energy and Climate Change.
He said Mr Mandelson was an "immense talent" who would be welcomed by the business community.
Of course we've had our ups and downs but we have also known each other for over 20 years and originally we worked very well together
Mr Mandelson said he was surprised but "proud" when the announcement was made on Friday.
He twice resigned from cabinet posts under Tony Blair's leadership - once over a loan from ministerial colleague Geoffrey Robinson and once over allegations of misconduct regarding a passport application for the Hinduja brothers.
He was later cleared of any wrongdoing.
The reshuffle could make Conservative leader David Cameron follow suit with his shadow cabinet to take account of the changes made to the government, including the creation of the new Energy and Climate Change department.
Chris Grayling, for the Conservatives, said the reshuffle reinforced Mr Brown's weaknesses.
He said: "He now has 10 ministers attending cabinet who are not members of the cabinet... and he has brought back people he sacked just a year ago.
"This is a back-to-the-future reshuffle and certainly not the change Britain needs."
Danny Alexander, for the Liberal Democrats, said: "Resurrecting ex-ministers from the political graveyard is not going to breathe new life into Gordon Brown's zombie government."
BBC political correspondent Jo Coburn said: "For Gordon Brown this was a sop to the Blairite wing of the party to basically say there would be a case of bringing the two wings of the party together.
"That was the political strategy as well, of course, as bringing some experience into the cabinet."
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