The conference will follow the publication of a report by former union leader Lord (Ray) Collins, commissioned by Mr Miliband in the wake of allegations of union vote-rigging in the contest for the party's parliamentary candidate in Falkirk.
Launching a national campaign to explain the reforms in London today, Mr Miliband said he wants to "build a new way of doing politics" and turn Labour into a mass-membership party "powered by the people".
The announcement will inevitably prompt comparisons with the special conference staged by Tony Blair in 1995, which stamped the new leader's authority on his party by scrapping the Clause 4 commitment to nationalisation.
Mr Miliband has already announced that he wants members of trade unions affiliated to Labour to be given the chance to "opt in" to membership of the party, replacing a system where their political fund levy is automatically passed on to Labour unless they opt out.
The move is designed to boost Labour membership from its current 200,000 and loosen the financial hold of union bosses over the party, but unions have warned that it could cost millions of pounds in lost donations.
On Monday, Mr Miliband said his proposals will give Labour the chance to tackle voter disengagement and become "a party that represents the beating heart of the British people" and gives its members "a real voice" on policy-making.
"The changes we are embarked upon are about this - about rooting our party in every part of Britain, including the workplaces of Britain," he said.
"Our links with trade union members provide us the opportunity to do that. But those links need to be real, local and vibrant.
"We need the three million nurses, engineers, shop workers, bus drivers, construction workers who are members of trade unions to be a proper part of our party.
"We need to reach out to people in every walk of life, including small businesses, entrepreneurs, and in every part of the country, South as well as North.
"We need to give all these working people a real choice about joining Labour - and then a real voice inside the party."
Lord Collins will consult widely over the summer before presenting detailed proposals for the implementation of the reforms to Labour's annual conference in Brighton in September, said Mr Miliband.
Meanwhile, Mr Miliband will embark on a series of town hall meetings to explain his plans.
Deputy leader Harriet Harman and MP Phil Wilson - who helped Mr Blair in the battle over Clause 4 and succeeded him as MP for Sedgefield - have been given responsibility for debating the changes with party members, and all shadow cabinet members will play a part in the national campaign.
Shadow Cabinet Office minister Jon Trickett and Treasury spokeswoman Rachel Reeves will work on further reforms to make Labour a mass-membership organisation, drawing on work done by US community organiser Arnie Graf.
At the next meeting of Labour's ruling National Executive Committee, in September, Mr Miliband will seek approval for the process to culminate in a special conference in the spring.
He said today: "If we succeed in this, then Labour has a historic opportunity to become a truly 21st Century party.
"A party powered by people, a party that can change a country that has a politics too often skewed to the interests of a wealthy and powerful few."
Mr Miliband sought to contrast his approach with that of prime minister David Cameron, who has faced a series of awkward headlines over his meetings with donors and the big business clients of his election guru, Lynton Crosby.
"Britain's working people don't get to have cosy dinners in Downing Street to discuss policy, like David Cameron's big donors," said the Labour leader.
"They don't have lobbyists looking after their interests, like the big tobacco companies do with Lynton Crosby...
"That's why they need a party that is open to them. That is on their side. A One Nation Labour Party for all the people of Britain, not just a few at the top."
Mr Miliband said Labour aimed to "open up our policy-making, clean up the lobbying industry and take the big money out of politics and... let people back in".
He urged activists to help him "build a movement again - a movement that makes change happen in communities across the country. And a movement that changes Britain."
Len McCluskey, general secretary of Unite, said: "We share Ed Miliband's vision to widen participation in the Labour Party and truly make it a mass membership organisation.
"Time and time again the Tories have demonstrated that they are a party for big business, more interested in putting the interests of a wealthy elite ahead of those ordinary people struggling to get by.
"Now more than ever we need a Labour Party that speaks for and acts on behalf of ordinary people."
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