A referendum on asset sales will be held by postal ballot over three weeks beginning on 22 November.
More than 327,000 people signed the Keep Our Assets petition against the partial sale of the country's power companies -18,500 more than needed to force a citizens initiated referendum.
Now the Clerk of the House has certified the petition, a referendum must be held, but the result will not be binding on the Government.
The announcement has been made on the same day that the Government opened the sale of shares in Meridian Energy to the public.
Voting in the referendum will open on Friday 22 November and close three weeks later, on Friday 13 December.
Prime Minister John Key says Cabinet has decided it will be held by postal vote, as it's the most cost-effective way of conducting a referendum, with a price tag of about $9 million.
The Labour and Green parties say the cost is justified as voters will be given the chance to have their say.