The Department of Treasury and Finance was formed on 1 July 2001 as a merger between the Treasury and State Revenue departments. On 3 February 2003, the Department also incorporated the functions of procurement management which had previously been the responsibility of the Department of Contract and Management Services.

The Department had three main functions: providing economic and financial management for the State government; collecting State revenue and administering the associated revenue laws; and undertaking a central contracting and tendering function.

The Office of Native Title, formerly part of the Department of Premier and Cabinet, became a business unit of the Department of Treasury and Finance on 6 April 2006. It later became an independent entity within Treasury and Finance that same year.

In 2007, responsibility for the Office of Shared Services was transferred from the Department of Premier and Cabinet to the Department of Treasury and Finance.

The Department of Treasury and Finance was redesignated the Department of Treasury with effect on 1 July 2011. Treasury was formed from the former Treasury and Strategic Projects business units of the Department of Treasury and Finance. The Department of Finance was established that same day.