Minister for Corrections Anthony Roberts commissioned the Shortland Correctional Centre. The extension to the existing maximum security Cessnock complex increases the number of beds to 580.

The project, which was part of the NSW government's $3.8 billion investment into increasing capacity in the state's prisons, has also created an additional 85 jobs for the region.

"Corrective Services NSW is a major employer in the Hunter Region and is pleased to be growing and strengthening that investment," Mr Roberts said.

"It's about the government's plan to actually make our community safer but at the same time, reduce re-offending and ensure inmates have the best opportunity when they leave jail to actually undertake full employment and become citizens that contribute to our society."

The maximum-security section of Cessnock Correctional Complex was renamed Shortland Correctional Centre in June after Lieutenant John Shortland, a renowned Hunter naval officer and explorer from the late 1700s.

The expansion included the construction of a health clinic, a sports and exercise area and a 4000 square-metre programs and industries building.

Corrective Services NSW Commissioner Peter Severin said the new facilities would help inmates address their offending behaviour and gain the skills and training they need to find employment upon their release.

"It will accommodate those that require a very high degree of control but at the same time, those who are ready to positively engage in work and education," he said.

"This centre will help fill an important gap that we have as a result of unprecedented growth in our prisoner numbers over a long period of time.

"We will get this infrastructure online which means we can do our jobs better."

The new maximum-security men's centre will welcome inmates in the coming weeks.

Work is continuing on the new 240-bed minimum-security wing in the neighbouring Cessnock Correctional Complex, which is expected to open early next year.

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