The department's mission is to maintain and enhance community security and to promote a fairer society in Ireland.

The mission of the Department of Justice is to maintain and enhance community security through the development of a range of policies and high-quality services which underpin: In July 2014 the department embarked on a comprehensive programme of change, including the recruitment of a new secretary-general following an independent review.

[3] The official headquarters and ministerial offices of the department are on St Stephen's Green, Dublin.

The Ministers and Secretaries Act 1924, passed soon after the establishment of the Irish Free State in 1922, provided it with a statutory basis and renamed it as the Department of Justice.

This act provided it with:[4] the administration and business generally of public services in connection with law, justice, public order and police, and all powers, duties and functions connected with the same (except such powers, duties and functions as are by law reserved to the Executive Council and such powers, duties and functions as are by the Constitution or by law excepted from the authority of the Executive Council or of an Executive Minister), and shall include in particular the business, powers, duties and functions of the branches and officers of the public service specified in the second part of the schedule to this Act, and of which Department the head shall be, and shall be styled, an t-Aire Dlí agus Cirt or (in English) the Minister for Justice.The schedule assigned it with the following bodies:[5] The name and functions of the department have changed by means of statutory instruments.