Fonterra's farmer shareholders have voted overwhelmingly in favour of the sale of the brands like Mainland and Anchor to a French company.
More than 88 percent of the votes cast at a special meeting backed the $4.4 billion sale to French dairy giant Lactalis.
The threshold required to approve the sale was more than 50%. Chairman Peter McBride says the Board is encouraged by the "strong mandate".
"It helps to demonstrate one of the key things that sets us apart from most other processors - our farmers have a direct say in the future of their Co-operative, and they've made the most of that opportunity."
ASB Bank estimated the sale proceeds would ultimately be worth about $4.5b to the economy, with farmer shareholders receiving an average tax-free payout of about $392,000 if the sale went ahead.
The sale to the world's biggest dairy group, French-based Lactalis, is the final step in Fonterra's transition to a slimmed-down New Zealand-based supplier of raw ingredients and high-value products to other manufacturers.
NZ First leader Winston Peters described the decision as "utter madness" and "economic self-sabotage".
"This is an outrageous short-sighted sugar hit that is just giving away New Zealand's added value to a company from a major EU country. There is now no long term security for New Zealand's farmers," he said on X.
"Three years after this deal starts, Lactalis can begin the three year notice to terminate the milk supply to these brands. Six years is meaningless for a long-term exporter. When it's over, it really is over.
"Meanwhile, Lactalis secures ten years of raw milk for its own consumer brands. It is astonishing that business commentators do not see the irony of this."
