Delegates at a special general meeting in Manchester have voted unanimously in favour of a series of radical reforms to restructure the co-op.
The planned changes to the cooperative group follow a troubled period for the northwest based mutual as Ralph Blunsom reports.
The chair of the Co-operative Group says the unanimous vote in favour of wide-ranging reforms as a "highly significant moment" for the mutual, which slumped to £2.5 billion annual losses after a period of crisis.
Ursula Lidbetter said: "I am delighted that our members have made clear their commitment to far-reaching reform of our governance with this unanimous vote.
"There is a huge task ahead of us if we are to deliver the reforms necessary to restore the Group's reputation and return it to health but the board will work hand-in-hand with our members to ensure that we seize this opportunity.
"It is vital that the right changes are put in place as soon as possible to build a more effective organisation for our members, customers and colleagues."
Britain's biggest union has welcomed the vote for reform of the troubled mutual.
Adrian Jones, national officer of Unite, said: "The vote for reform is a welcome step in the right direction and one which we hope will put the Co-op Group on the road to stability.
"Going forward it is vital that our members and employees have a voice in the reform process for it to succeed and ensure the Co-op Group has a fighting chance while retaining its unique values and ethos."
Undertakers, students and supermarket customers will all be represented in a key poll on the future of the Co-op but none will have an individual ballot.
Block votes will decide whether the troubled food-to-funerals group takes a step towards a radical shake-up seen as vital to securing its future.
The poll will canvass support on four key principles taken from a reform plan drawn up by former City minister Lord Myners, and must achieve a simple majority of over 50% to be taken forward.
The byzantine voting structure includes a 22% share for independent societies and affiliated organisations, and the rest made up of regional boards, elected by the Co-op's area committees.
Former City minister Lord Myners wants to replace this with a slimmed-down "plc and beyond" structure staffed by professionally-trained directors.
The former Marks & Spencer boss was appointed a director of the Co-operative Group in December but announced he is to leave following this weekend's vote.
He has said it was apparent to him from the first time he attended a board meeting that not one of its members had the ability to address the complex issues faced by a group burdened with £1.4 billion of debt.
This weekend's ballot will be decided by representatives of its independent societies and affiliated organisations - who hold 22% of the vote - and others voting on behalf of its regional membership boards making up the remaining 78%.
A crucial poll will see the Co-op face its future later when key principles on radical reform of the troubled mutual go to the vote at a special meeting.
Former City minister Lord Myners has proposed a major shake-up of the food-to-funerals business after a disastrous period saw it slump to a £2.5 billion annual loss - its worst ever - in 2013.
But Lord Myners fears that traditionalists within the 150-year-old organisation are "still stuck in denial" about its problems and will not support the plans.
These include sweeping away the existing 20-strong board of representatives from the co-operative movement, who currently include an engineer, a plasterer and a retired deputy head teacher.