Far-reaching reforms that change Labour's historic links with trade unions were backed by 86% to 14% at a special conference today.
Most speakers at the London meeting praised the changes to the party's structures that were put forward by Ed Miliband following controversy over Unite's involvement in the selection of a Labour candidate in Falkirk last year.
The Labour leader insisted the biggest transfer of power in its history would help build a strong party that would help make the voices of working people "louder".
Ed Miliband applauds during a special conference on reforms to the Labour Party
A defiant Len McCluskey said the changes would increase trade union involvement in the party and insisted Unite was "going nowhere".
Miliband told unions, MPs and other delegates: "I am proud of our link with working people and with trade unions.
"I want to hear the voices of working people to be heard louder in our party than ever before and in the 21st century not everyone wants to be a member of a political party."
Miliband said he had taken a "big risk" last July when he proposed the reforms.
"I did not believe we could face up to the challenges the country faced if we didn't face up to the challenges faced by our party."
He told delegates that some people in Britain had felt that Labour had lost touch with them, adding: "These changes are designed to ensure that this party never loses touch again."
The changes will hit the number of union members affiliated to the party as well as funds.
Unite's executive will meet next week in the wake of today's vote to discuss whether to cut its affiliation with Labour.
The union has one million members affiliated to Labour worth £3m a year but around 400,000 of those do not vote Labour, so Mr McCluskey has said he is "honour bound" to review its funding.
It has donated more than £11 million to the party since Miliband became leader.
McCluskey told the conference the reforms would "starts to take us down the road of involving more trade unionists in the business of the party".
He defended Stevie Deans, the union official who resigned from his job at a giant oil refinery after the row over the Labour Party selection process, and said the changes vindicated Unite.
"This whole process began amidst a firestorm of political and media attacks on my union - because we have been doing what everybody now says they want us to do, encouraging our members to join the Labour party, to take part in its democracy within the rules to help make our parliamentary party more representative of our voters in the country as a whole, and yes, to select Labour candidates who share our values.
"That's not a crime in a democracy.
"So let me make one thing crystal clear. The party has said, the police - who should never have been involved - have said and I'm saying it here today, my union did nothing wrong.
"The smears and the lies and the innuendos will not deflect us from our political strategy but they do sometimes claim victims.
"That's why I ask this conference to show its support for Stevie Deans, a decent working man, a loyal Labour member and a trade unionist. He's been hounded out of his job."
He added: "Let me finally say to those elements inside the party who seek to edge us out, or to the grandees who snipe from the sidelines - this is our party and we are going nowhere."