The Inspectorate became part of the Department of Corrections when the Department was separated from the then Department of Justice in 1995.

The current Office of the Inspectorate was established under the Corrections Act 2004 as a dedicated complaints resolution, investigation and assurance function. The Office is independent of prison management, and its staff are independent of the activities they review.

Inspectors can also investigate complaints from offenders in the community.

In early 2017, the Office of the Inspectorate was enhanced to provide greater assurance about the fair, safe, secure and humane treatment of prisoners, operational issues and best practice, and any emerging risks in relation to prisons.

The Inspectorate now has a Chief Inspector, two Principal Inspectors and 14 inspectors, along with other specialist and support staff.