A wing of the Cessnock Correctional Centre will be closed, with the facility running well under capacity.
A quarter of Cessnock's cells are empty and will be one of several jails to be "temporary consolidation" by NSW Corrective Services, with the state's post-pandemic prison population "significantly lower than anticipated".
Across the state's prison network can accommodate about 15,600 people, however currently the average population is around 12,300 inmates or 78 per cent of its capacity.
Cessnock Correctional Centre is running at 75 per cent capacity. The gaol can hold 655 inmates, but currently only holds 491.
Under utilised parts of the prison will be closed on February 12. Wings at Bathurst, Goulburn, Long Bay Jail Hospital and the Metropolitan Special Program Centre will also shut.
Despite the closures, Corrective Services NSW said there would be no job losses or significant impact on prisons.
"CSNSW is constantly reviewing its operating bed network to ensure that it supports the current inmate population, anticipated growth or decline, and operating environment," A CSNSW spokesperson said.
"The changes will ensure a greater use of beds that are modern, not aged, and improve inmate management and service delivery by accommodating those in custody in areas that are more fit-for-purpose."
The Public Services Association said the upcoming closures had been poorly handled, and that the union hadn't been made aware of the plans.
However, CSNSW said the PSA was consulted about the decision.
"Any staff affected can remain within their existing centre or correctional complex," a CSNSW spokesperson said.
"CSNSW is committed to working closely with the PSA and welcomes feedback to ensure any changes are informed and supported."
