The $700 million Clarence Correctional Centre at Lavadia, south of Grafton, at capacity will house up to 1,700 inmates.
Prisoners for the new facility will come from across New South Wales, including the existing Grafton jail.
At least 300 personnel have been employed so far and recruitment continues for other positions.

The State Government has said the prison would be the safest in NSW, with extensive security measures such as 1,650 cameras as well as biometric technology monitoring the locations of all prisoners.
It is estimated the prison will inject more than $500 million into the Clarence Valley economy over the next 20 years.
by Angus Jones