The Labour leader's speech was warmly received, with one union leader saying it was the best he had heard him make.
Len McCluskey, general secretary of Unite, described the speech as a "tour de force", which showed that Mr Miliband was a prime minister-in-waiting.
Mr McCluskey said: "He has projected himself as being on the side of the people, working to embrace ordinary men and women and challenging the Conservatives' austerity programme. It was probably the best speech I have heard him make - it offers hope for young people because what he said on apprenticeships was first-class."
"This was the day Ed Miliband showed that he was prime minister material," said Unison general secretary Dave Prentis. "He has shown that he is not afraid to take on the banks or big business to make them operate in the interests of the nation to at last begin to redress the gross inequalities in our society.
"But he offered little hope to the millions of low-paid public service workers - teaching assistants, dinner ladies, care workers - who are going through massive pay cuts, their jobs threatened and their services privatised. Until he can offer them hope, it will be difficult for them to vote Labour again. One Britain should include these workers."
CBI director general John Cridland said: "Business agrees with the importance of building an economy for all. In particular, I believe that Ed Miliband was right to put so much emphasis on education for the forgotten 50%. Unless everyone has the skills to contribute to the economy, they are unable to benefit from it."
John Longworth, director general of the British Chambers of Commerce, said: "Ed Miliband extended an olive branch to business by saying that Labour wants to engage with the private sector and small businesses. Many companies in the real economy will want to hear more over the coming months about Mr Miliband's promise to support businesses focused on long-term growth."
Shadow health secretary Andy Burnham said: "This is a major turning point for us. The country didn't want to listen to us in the first two-and-a-half years, they said go away and lick your wounds. That's what we've gone and done. Now we are coming back, we are coming back strong, we have got a clear vision, that's been set out here. Now we need to bring forward the policies that make it real."
But Conservative Party Chairman Grant Shapps said: "To prove he is credible, Ed Miliband had to do more than give a speech to rouse the Labour party faithful; he had to show that he had learned from the mistakes that Labour made in office.
"Instead he failed to back our welfare cap, failed to back our immigration cap and still stands for more spending, more borrowing and more debt - exactly what got us into this mess in the first place. Sadly, Labour isn't learning."