"Last Tuesday, Cabinet agreed on a proposal from me to introduce legislation under urgency when Parliament resumes to remove the remaining 41 products from the shelves until such time as their low-level of risk can be proven," Mr Dunne said.
He said he would have made the announcement earlier, but he did not want to encourage stock-piling of the drugs.
The emergency legislation will be introduced when Parliament resumes on May 6 and will be passed under urgency.
"I'm expecting it to be passed that particular week and to take effect pretty much immediately afterwards," Mr Dunne said.
This meant there would be no psychoactive substances for sale in New Zealand for "some considerable amount of time".
In Rotorua there are four stores in the CBD holding interim licences to sell legal highs and about 150 outlets selling them nationwide.
Rotorua mayor Steve Chadwick said she was pleased the Government had bowed to public pressure.
"As with pharmaceuticals, you must prove there is no harm before they are introduced to the public - these should be just the same."
But, she said it was "the clumsiest piece of law-making ... she had ever seen".
"These things are evil and the damage to communities is huge.
"The pressure from communities was not going to go away."
Mrs Chadwick said the council would continue to hear submissions to its LAPP, but "it clearly will not need to be enforced".
Rotorua MP Todd McClay said the ban was appropriate and long overdue.
"I view this as a win for the hundreds of people I marched beside in Rotorua a few weeks ago and I will happily cast my vote to take these last 41 products off the shelf."
Mr McClay urged Rotorua's legal high retailers to take immediate action by demonstrating their responsibility to the community.
"As of today, retailers who stock these products should send them back to the manufacturer for a full refund," he said.
Mr Coffey said it was a triumph for the opposition and the people on the streets who applied pressure and forced the Government to take action.
"Whichever way it goes we will see the end of these CBD tinny houses."
Mr Coffey wanted to know if the Government had counselling and rehabilitation services in place to help those who had already developed a habit.
"People will now be stocking up on these products, they will be sitting on people's shelves, and inevitably, there will be an underground market for them."