Those 202 staff members who haven't been vaccinated have been placed on paid special leave from Sunday for the time being.
Corrections also decided last week that all private visitors aged 12 and over to prisons nationwide must be fully vaccinated by December 9.
"This is not a decision we have made lightly, and we acknowledge the significant impact this will have for people in prison with unvaccinated friends and whānau," chief custodial officer Neil Beales said.
"Ultimately, we take our duty of care to people in prison and the wellbeing of our staff seriously, and we must act to prevent them from the very serious harm that Covid-19 poses.
"Requiring visitors to be vaccinated lessens the potential for Covid-19 to be introduced to a prison. This will also help minimise impacts on the wider health system, which could face additional pressure if a Covid-19 outbreak occurred in a prison."
Corrections said it was confident the special leave would have no impact on its operations.