A jump in the national number of inmates means two moth-balled units at Tongariro Prison are being brought back into use.
The Corrections Department says two 60 bed units at the low security men's prison will re-open at the beginning of next month.
It also aims to re-open some units at Waikeria Prison in Te Awamutu to cope with increasing numbers of prisoners. Double bunking is to be increased at five prisons.
Last month, the number of inmates held in prison or police station cells reached 8434 - 23 fewer than the previous high in 2007.
Re-opening the units at Waikeria means the department needs to hire new prison guards.
Assistant general manager Leeanne Field believes the recession will make the prospect of becoming a prison officer more attractive.
Recruiting by West Australia
The Corrections Association says the department has found it difficult to staff Tongariro Prison in the past - due to its remote location, which is one of the reasons why the two units were closed.
A recruitment drive was held late last year in Auckland, Wellington and Christchurch by the Corrective Services Department in Western Australia.
The association says the campaign has been successful.
President Beven Hanlon says 20 officers left Rimutaka Prison in Upper Hutt about a month ago to work in Western Australia.
Mr Hanlon says the union is hearing of two or three prison guards every week who are moving over there.