A prison officer at Spring Hill Prison in Waikato is facing a drug smuggling charge.
The female officer is being prosecuted under the Misuse of Drugs Act. She was suspended last week after evidence was uncovered of drug smuggling at the jail.
The Department of Corrections is conducting an operation targeting staff suspected of corruption.
A unit manager and a Corrections officer have also been arrested at Rimutaka Prison, north of Wellington. The department says dismissals are likely in coming weeks.
Corrections chief executive Barry Matthews says a small number of staff engaging in corrupt behaviour are being monitored.
He says the department will identify those who are breaking the law and that Corrections will work with the police to bring criminal charges.
Mr Matthews declined to be specific about the case of the Spring Hill prison officer, saying the matter has to be heard in court.