Auckland Prison at Paremoremo is to begin its first intensive drug treatment programme for inmates.
The Corrections Department has selected Odyssey House to deliver the programme, which will target prisoners serving sentences of between four and 12 months.
It will start in mid-September.
Odyssey House says 89% of serious offenders are affected by alcohol and drugs in the period leading up to their offence.
Its chief executive, Christine Kalin, says for some prisoners it will be the first opportunity they have had to receive treatment.
She says the programmes reduce reoffending, with evidence that every dollar spent on drug and alcohol treatment saves the taxpayer $5.