Mt Eden and Auckland Central Remand prisons are now using a single entrance where people are checked for contraband items.
Anyone entering the site will have to go through metal detectors and x-ray machines in efforts to stop smuggling.
The authorities hope the initiative will prevent contraband items such as drugs, weapons and mobile phones getting in.
The manager of the prisons, Grace Smit, says dedicated staff are being vigilant in checking everyone who enters the site, irrespective of their role or their activty.
She says the initiative will bring the facility into line with other, newer prison sites around the country.