Police have signed a contract with Cooneen Protection for the manufacture and supply of the new gear. Cooneen also provide body armour for London's Metropolitan Police force.
Police are spending $20.7m over four years to make the replacements.
"It's a significant investment but the safety of our staff is paramount," Bush said.
"To keep communities safe, first police must keep themselves safe.
"So today I'm proud to announce we are investing in a new body armour system that will help keep police safe.
"With more than a million interactions with the public every year, the vast majority is New Zealanders engage with us appropriately. However, it's unfortunately the nature of police work that some people want to harm us."
Existing body armour remained fit for purpose while the new armour was introduced over the next three years, he said.
Both current and new armour meet international safety standards for stab and ballistic resistance.
